RV 7 way, 7 wire molded plug with center pin for back up lights. Color coded for general open flatbed trailers.
 
* These 7 wire molded plugs include the center pin required for trailers that have backup lights, but can also used for those that do not. Just cap off additional wire. The center pin on the RV type plug with 7 wires is used for trailers with backup lights. Color coding is for non RV type trailers, but connector layout is the same as shown in pic. Both types are identical otherwise and fit the same "RV Style" receptical on the vehicle.