QuestCraft 20' RV'S BOAT TRAILER TAIL LIGHT ADAPTOR &WIRE PLUG W/ WIRE KIT FOR TOWING This Item is Brand New! TAIL LIGHT ADAPTOR PLUG WITH 20 FT WIRE KIT RV'S BOAT TRAILER These adapters have flat pins and they are available in both car and trailer end configurations. The wire is tapped into the backup lights to disengage the trailer's brakes when the vehicle is reversing. The 7-way RV and 4-flat configuration is a Ready Connect car end connector.