Bosch style 12 volt car relays. 30/40 amp. Use as a SPDT relay (5 wires) or a SPST relay (4 wires -87a not used) Relays can be used to turn on additional car lighting when trigger by car stereo remote wire, fog lights or adding led strips as blinkers to tailgates. Copper wiring, not copper clad aluminum found other style pigtails.