Set includes four jumpers to fit many popular relays on Honda, Nissan, Toyota, newer Ford and GM mini micro relays as well as International trucks. Set comes in blow-molded case for storage. Simply remove relay to be tested, insert correct jumper and insert relay into jumper. When using grey four pin jumper be careful to align pins on jumper and relay correctly. No need to pierce wires or connect multiple jumper wires. Jumpers have tabs for clamping and flat pads to place test leads on.