KT LED 7-PIN LARGE ROUND TRAILER SOCKET LED Trailer Plug Range KT LED Trailer Plugs and Sockets have many unique features that make this range far more superior than any other range on the market. This specific range of trailer plugs are one of a kind designed with an inbuilt LED Circuit Tester to detect any faults between your vehicle and trailer connections via a visual check through six illuminated LEDs. The KT LED range have an on/off switch compatible with all other trailer plugs on the market.