The trailer circuit testers allow one man to test trailer circuits quickly and easily. The Multi Trailer Tester Jobber Pack allows one person to test all connection types.; Features and Benefits: Plugs into the vehicle side socket; LEDs indicate that each circuit is working; Eliminates guesswork; Winged grip for easy installation and removal from electrical connector; 3-Way Trailer adapter adapters 7-way flat (spade) to 6-way round and 4/5 pin type connections; Includes: 7-Way Flat (Spade) Pin Trailer Circuit Tester (#7893) • 7-Way Round Pin Circuit Tester (#7865L) • 6-Way Round Pin Trailer Circuit Tester (#7897) • 4/5 Pin Harness Checker (#7866) • 3 Way Trailer Adapter (#8000)