7 Blade Extension | etrailer Designed for use with your 24" long SuperHitch SuperTruss receiver extension, one end of this no-splice wiring harness plugs into your truck's 7-way blade trailer connector. The other end with the SuperTruss extension Installs quickly and easily - no splicing required Measures 28" long Made in the USA W6024 Tork Lift 2-Way Wiring for 24" Super Truss Extension - 7-Pole Blade-Style Trailer Amazon: 7 blade trailer extension Amazon: 7 blade trailer extension. Skip to main content. Lavolta 7-Way Trailer Extension Cord Wire 4 Ft - 7 Pin Connector Plug for RV Blade Socket - Connects Lights, Power from Trailer, Caravan, 5th Wheel to Truck or Van - Heavy Duty & Weatherproof. 4.3 out of 5 stars 10.