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When your tow vehicle and trailer use different 7-way plug styles, this adapter saves the day. The Custer Trailer Connector Adapter #ADP7R-7B has a standard 7-way blade female on one end and a 7-way round male on the other. It bridges the gap between the two connector types so you can hook up and tow without cutting or rewiring.
Instead of chasing wire diagrams or swapping plugs, this adapter just plugs in and works. The round male end connects to the 7-way socket on the vehicle, while the blade female end accepts your trailer’s 7-way blade plug. It’s a clean, solid connection that keeps your wiring intact and ready for the road.
This adapter is made strictly to change the connector style—it doesn’t convert signal types or combine separate circuits. If your setup already uses matching combined stop/turn circuits and a standard 12-volt charge line, it’s ready to go. You get a reliable physical connection between round and blade systems without adding unnecessary electronics.
Whether you’re pulling different trailers or switching between vehicles that use different 7-way formats, this universal fit adapter lets you move from one hookup to another with minimal effort. Keep it in your toolbox or glove box—it’s one of those small parts that makes a big difference when you need it most.
Customer Satisfaction Score:
97% were satisfied with this product
3% of customers were not satisfied
Ratings & Reviews
as expected totally happy
Got it quick
Awesome product
Excellent quality. Great company to do business with. They care what people think of their products and service! Thank you!
The trailer connector is exactly what we ordered. etrailer customer service was great all the way around. Shipping was fast and showed up on time.
Bought to connect trailer wiring to aJohn Deere 5075. Checking wires now just in case I need to switch any wires as suggested on note attached to the connector. Left turn right turn are correct. Think the 12v needs to be switched, I think its wired to electic trailer brakes. Excellent product.
I am using these adapters to allow Custer wireless rechargeable tail lights to function on the back of my farm silage wagons when hauling from the chopper. The sending units for the lights are “ truck type” 7 pin flat whereas tractors are 7 pin round. A possible suggestion would be to make the cord on the adapter about 5 feet long to allow the transmitter to be located higher on the cab post and out of the heavy steel and cast iron congested area at the back of the tractor. So far the units are working well. Thank you
Love this adapter. I use it to haul my dump trailer and flatbed trailers with my tractor, and it's exactly what I needed to do so to have active ligjts and brakes from tractor to trailer. Highly recommended
The 7 round to 7 way blade adapter works excellent.
very helpful and good communication.
As has been typical w eTrailer, received our product in a very timely quick manner, and was as ordered. This pigtail is of good quality, and worth the little extra $ over cheaper variants. Works the treat in connecting our road trailers to our farm tractor so we have lights and turn signals for our on road transits of these trailers w our Farm tractor. Dump trailers, horse trailers, flat bed trailers etc.
Wes
3/8/2024
This item has stood up well to heavy use and weather exposure over the last year since purchase !
Jesse M.
3/12/2024
Info for this part was:
At etrailer we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time.
Dennis
2/9/2025
We hook a tractor to our flatbed gooseneck trailer to haul bales, nice to have lights and turn signals.