Nilight 7 Way Blade Trailer Connector Tester with Red LEDs Indicators Heavy Duty 7 Pin Trailer Light Wire Circuit Tester Trailer Hitch Wiring Tester, 2 Years Warranty. It comes with strong fixation and can hole the adapter in place and with rugged nylon housing. Clear and obvious labeling of each light enable you quickly to identify the working and faulty circuits at a glance.