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Custer Trailer Connector Adapter w/ Dust Cover - 7-Pole Round Pin to 7-Way Blade

Custer Trailer Connector Adapter w/ Dust Cover - 7-Pole Round Pin to 7-Way Blade

Item # F77R
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This adapter converts your 7-way round pin connector to a RV-style, 7-way blade connector. Built-in ABS plastic cover protects the 7-way blade terminal from dust and moisture. Pull grips on the round end make the plug easy to install and remove. Lowest Prices for the best trailer wiring from Brophy. Custer Trailer Connector Adapter w/ Dust Cover - 7-Pole Round Pin to 7-Way Blade part number F77R can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (39)
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Brophy Trailer Wiring - F77R

  • Wiring Adapters
  • Single-Function Adapter
  • 7 Round - Round
  • Plug and Lead
  • 0 - 5 Feet Long
  • 7 Round - Blade
  • Brophy

This adapter converts your 7-way round pin connector to a RV-style, 7-way blade connector. Built-in ABS plastic cover protects the 7-way blade terminal from dust and moisture. Pull grips on the round end make the plug easy to install and remove.


  • Adapter converts your 7-way round pin connector to a 7-way RV-style connector
  • Built-in cover protects the 7-way blade end from dirt and moisture when not in use
    • Hinged cover opens 180 degrees for effortless connection
  • Pull grips on the 7-way round pin connector make plug easy to install and remove
  • ABS plastic construction is strong and durable
  • Flexible wire between plugs provides wide range of motion


  • Overall length: 14"
  • Length between the plugs: 6"

This adapter allows the 7-Way, round-pin, vehicle-end connector to work with the 7-way blade, RV-style, trailer-end connector on the right.

7-Way, Round-Pin, Vehicle-End Connector

7-Way, RV-Style, Trailer-End Connector

F77R Custer Trailer Connector Adaptor with Dust Cover - 7-Pole Round to 7-Blade

Customer Reviews

Custer Trailer Connector Adapter w/ Dust Cover - 7-Pole Round Pin to 7-Way Blade - F77R

Average Customer Rating:  4.6 out of 5 stars   (39 Customer Reviews)

This adapter converts your 7-way round pin connector to a RV-style, 7-way blade connector. Built-in ABS plastic cover protects the 7-way blade terminal from dust and moisture. Pull grips on the round end make the plug easy to install and remove.


This product did not work. The diameter of the 7 pin receptacle plug was 1/8” narrower than my trailer plug. It fit perfectly into the 7 way blade receiver plug on my truck. I called customer service. She called manufacturer and manufacturer said there must be something wrong with my trailer plug. My trailer plug came standard on the trailer. Unfortunately no inside diameters are provided so one cannot measure before ordering. I am returning the product but was told I have to pay for shipping. etrailer has such a good reputation. I am really disappointed in this experience.

I will have our customer service team reach out to you. This adapter is intended to work with most 7-way blade, RV-style trailer side plugs.
-- Etrailer Expert Jenny N - 10/25/2021


Worked well as adaptor from Great Plains no till drill wiring harness to use on truck.


I have ordered several of these in the past from etrailer. Great product, quick shipping, an overall Great company to do business with.

Ive heard no complaints from our employees who use these.
Jeff K - 09/21/2017


Worked perfectly. Nice for towing farm equipment with a normal common plug from truck. Works great on my Ford trucks.


Received quickly, worked with brake lights & turn signals, but not headlights or parking lights


Exactly what we were looking for. Customer service was great and found the right product for our application in a few minutes, shipping was quick. We are on the road with lights and no rewiring.


Product didnt work for my application even after talking to a tech and explaining what i needed after i returned the original i ordered so yeah good luck


Was exactly what I wanted. The pictures online made it easy to identify the correct product so it was great to get the right part the first time and on time.


Been looking for this application locally for a while. Happy to find it here. Haven't used it yet but it looks well made.


Worked as listed. E-trailer has provided yet another good product delivered on time. Thanks


Best adapter for the money. I am using it on farm equipment, so i can have lights when I tow with my truck.


It works perfectly for what we needed!




We have ordered 2 of these for our shop and love them. great quality not cheaply made. great customer service and fast delivery.


Looks Heavy-Duty. We'll see how wiring matches-up!


Works exactly as intended. I don't use it a lot, but I am happy with it.


I placed two orders recently. The website is organized and I was able to find what I needed. I spoke with Customer Service and they were nothing but helpful. I will definitely use them again.


Works great, Had to switch a few wires other than that works perfrect.


Product showed up in a couple of days and works exactly as advertised , I couldn't of been happier with the whole experience.



This is a great product. Fits and works as described. It is built well and has lasted the first 6 months of use.


Received ontime shipment easy website to figure out what I needed. Will use again



Works perfect for 7-round to 7-flat.


Product works perfectly

Show More Reviews

Ask the Experts about this Brophy Trailer Wiring

  • RV 7-Way to Round 7-Way Adapter Recommendation
    The part # F77R will plug into the RV style 7-way you have installed on your 2013 Ford F-250 and then will provide you with a 7-way round socket for your trailer to attach to. I attached a review video for you to check out as well.
    view full answer...
  • Recommended 7-way Round Pin To 7-Way Blade Adapter
    Based on your pictures, you need a 7-way blade adapter to 7-way round trailer end. I have just what you need. I recommend the Custer Trailer Connector Adapter w/ Dust Cover - 7-Pole Round Pin to 7-Way Blade # F77R.
    view full answer...
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  • Recommendation to Connect RV Style 7-Way on Truck to Round Pin 7-Way on Trailer
    In order to connect the 7-Way RV style connector (flat/blade pins) to the 7-Way round pin connector on your trailer, you will just need the Brophy Custer Trailer Connector Adapter # F77R. This adapter will plug right into the standard RV style 7-Way on your Silverado and provide a round pin connector for the trailer to attach to. I have attached a short video demonstration on this adapter that you can also check out.
    view full answer...
  • 7-Way Round to 7-Way Blade Adapter
    Since your light plugs into a 7-way round you'd actually need the opposite adapter than the # F77R. Which for that you'd just need the part # PK12728.
    view full answer...
  • Adapter for 7-Way Blade Trailer Connector to 7-Way Round Trailer Connector
    There is an adapter for you that will allow the 7-way blade connector (sometimes called a 7-way flat) on your GMC truck to work with the 7-way round connector on your trailer. If you take a look at the accompanying photo, that's what your connectors should look like; if so you will simply need Adapter # F77R and you'll be set! I have added a link to a video review of this adapter for you to check out as well.
    view full answer...
    Image 1 for
  • 7 Way Flat to 7 Way Round Adapter Recommendation for Use In Norway
    I wish I had something direct that I could recommend for you, but honestly your best option would be to find a local vehicle-side trailer wiring connector, remove your current one and then wire it up to match the connector on the trailer you have. In the off chance that the 7-way rounds in Norway are the same as the style here in the US you could use a 7 Way RV-Style (Flat Pin) to 7 Way Round Pin # F77R. I attached a couple wiring diagrams that you can check out to see the
    view full answer...
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  • Adapter From 4-Way Vehicle Side to 7-Way Trailer Side Connection
    The Tow Ready Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector # 30717 will connect to the vehicle side so the ground wire will need to be connected to your vehicle not the trailer. That ground wire is required for proper function of your adapter. The other wires if not used can be taped up and stored out of the way. I recommend using the mounting bracket # 18138 and the no drill # 18140 to secure this adapter. Since the trailer has a 7-way connection, it is very possible that...
    view full answer...
  • Adapter for 7-Way Round Pin on Trailer to 7-Way Blade on Ford F-150
    There are 7-Way blade style to 7-Way round pin adapters available that you can use such as # F77R. And if you want to change the trailers from round pin connectors to blade style you can use # PK12706. I have included a link to our article on various trailer connectors that has various diagrams that show the pin functions of connectors which will making replacing the existing connectors easier.
    view full answer...
  • 7 way Flat to 7 way Round Adapter Recommendation
    We have the Brophy adapter part # F77R which goes from a flat 7-way on a vehicle to a round 7-way on a trailer. I don't know what vehicle you have so I can't recommend a way to install a brake controller but we can recommend a controller. For a brake controller I would recommend the Prodigy P2 Brake Controller part # 90885. This is our best selling brake controller because of how well it works and how easy it is to setup. This is a proportional brake controller that senses the amount...
    view full answer...
  • 7-Way Extensions for 48 inch or 10 Foot for Camper
    To extend a 7-way 48 inches you'd want the part # TLW6048 which comes with a 7-way male on one side and female on the other. If instead you were looking for 10 feet the part # TLW6510 would be what you'd need. These are the best options available for what you are looking for!
    view full answer...
  • Availability of Watertight 7-Way Trailer Wiring Connector
    We do offer a watertight 7-way trailer connector setup with the EZ Connector Magnetic 7-Way Trailer Connectors w/ Watertight Seal # 319-R7-02 which installs in place of a standard trailer 7-way. I attached a review video for this for you to check out as well.
    view full answer...
  • Adapter Availability to Go from 7-Way Round to 7-Way Blade
    Sounds like you are either looking for the part # F77R which has a 7-way blade male and a 7-way female round connector or the part # PK12-724 which has 7-way round male and 7-way blade female.
    view full answer...
  • Trailer Wiring Extension for a Tall 2018 Ram 2500 Power Wagon Towing a Rental Trailer
    We do have various trailer wiring extensions you could use. If the rental trailer has a 7-Way blade style connector you could use an extension such as # C56080. Granted this one is 7 feet long but it costs less than shorter extensions and who knows when the additional length might come in handy. If the trailer takes a 4-Way you could use 12 inch extension # HM48145. Need more length? There is a 48 inch 4-Way extension too # HM47115.
    view full answer...
  • Can the Custer Trailer Connector Adapter # F77R be Used to Tow a 5th Wheel with a Kenworth Truck
    The Custer Trailer Connector Adapter # F77R is meant to go from a trailer with a 7-Pole Round connector to a 7-Way Blade connector. I believe that you need the exact opposite which can be found with the Pollak # PK12-724. You will need to take note to see if your 7-Way on your Kenworth has separate taillight wiring or not. If you test the pins on your 7-Way Round with a circuit tester # PTW2992 and find that the stop light signal has its own pin then you will need to splice in a converter...
    view full answer...
    Image 1 for Image 2 for Image 3 for
  • Comparing the Wesbar LED and Incandescent Agriculture Trailer Light Kits
    The price difference between The Wesbar LED Light kit # 54003-041 and the Wesbar Incandescent Light Kit # W002676 is due to the cost of producing LED lights versus incandescent light bulbs. LED light are quite a bit more expensive to make than incandescent lights. That being said, LED lights will last longer and use less power than their incandescent counter parts, so I do suggest going with the LED option. It should be noted that both the LED # 54003-041 and Incandescent # W002676 will...
    view full answer...
  • Adapter from Truck with 7-Blade to Camper with 7-Round Connectors
    An extension is going to be male on one side and female on the other. We have a 4 foot extension, part # TLW6042, that's a 7-way on each end. We don't carry an 8 foot long extension but we do have a 10 foot, part # TLW6510, that should work for you.
    view full answer...
    Image 1 for
  • Weight Distribution System and Shank for a ToughCountry Deluxe rear Bumper
    I have a solution for you but no ball mount is going to extend out that far and have anywhere near the 12,000 lbs to 15,000 lbs capacity you are needing. I recommend the Strait-Line Weight Distribution w/ Sway Control - No Shank - Trunnion Bar - 17K GTW, 1,700 lbs TW item # RP66075 with the Reese Weight Dist Shank - 12-1/4" Long - 2" Drop to 6-1/2" Rise item # RP54970. This system will give you a 15,000 lbs capacity and extend past your ToughCountry Deluxe Rear Bumper. For the ball there...
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  • Wiring a 2013 Ford Explorer with 7-way Round Pin Connection for Electric Brakes
    On your 2013 Ford Explorer, you have everything you need for your trailer with brakes. The Prodigy P2 Brake controller # 90885 with wiring adapter # 3035-P will give you the trailer brake controls to complete your tow package. It sounds like you have a 7-way with round pins where most factory systems will come with the 7-way with blade connection...but either way, we have what you need to connect your trailer. If you have a 7-way round pin, then you can use the Pollak Trailer Connector...
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  • Recommended Wiring Harness for 2006 Toyota Sienna to Tow a 6 Round Pin Tent Trailer
    Good news! I can help you with wiring up your tent trailer for your 2006 Toyota Sienna. First you will need the # 118304, which will provide you with a 4-way wiring harness and then I recommend installing the # ETBC7 this will give you the 7-way blade style connector which is more common than the 7-way round that your tent trailer has, so if you get a different trailer in the future you will not have to rewire your connector. To adapt your 7-way blade to the 7-way round we have the Brophy...
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    Image 1 for
  • Parts Needed to Add a Brake Controller on a 2013 Jeep Grand Cherokee With or Without the Tow Package
    Since you don't have the trailer towing package on your 2013 Jeep Grand Cherokee you do need to start off by installing a 4-Way connector. I recommend the Tekonsha T-One # 118425 as we have found Tekonsha to be one of the most reliable wiring companies that we carry. To have 7-Way and 4-Way connectors on your Jeep you also need the Universal Wiring Kit # ETBC7. This connects to the T-One and give you both connections that you need. It also includes everything you need for the 7-Way to...
    view full answer...
    Image 1 for
  • Availability of 7-Way Round Pin Wiring Extension
    We do offer quite a few types of trailer wiring adapters/extensions that can be seen by clicking on the linked page. Just select the vehicle end you need (we offer both 7-way round and 7-way flat blade style connectors) and then the other end you need. For a 7-way round pin to a 7-way blade you can use part # PK12-724 or # HM47425. Or for a 7-way blade to a 7-way round use part # 47595 or # F77R. These products feature one male and one female connector. We do not have a male 7-way round...
    view full answer...
  • Brake Controller Recommendation for a Trailer with Electric Over Hydraulic Brakes
    I have a solution for you, but the Prodigy RF Brake controller part # TK94FR is not compatible with electric over hydraulic brakes. Instead I would recommend the Prodigy P2 Brake Controller part # 90885 as this controller is compatible with EOH brakes. The Demco Hydraulic Brake Line Kit # DM5425 would work fine with AL-Ko calipers. The Adapter part # F77R would work for converting the 7-way round he has on his trailer. A better solution would be to not use an adapter and match both the...
    view full answer...

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Info for this part was:

Employee Dan D
Written by:
Dan D
Employee Michael H
Expert Research:
Michael H
Employee Jameson C
Expert Research:
Jameson C
Employee Jeff D
Installed by:
Jeff D
Employee Wilson B
Updated by:
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