The relay kit includes essential parts necessary to wire twin pump Mustang (12-1 or Challenger/Charger (12-154/12-176) modules to a vehicle. The installation starts with two high quality HELLA 40A relays, as well as relay sockets with 10 ft wire lengths, 12GA primary wires, 16GA secondary signal wires, and heat shrink sealing connectors to complete you installation. Also included are two fuse holders and 30A fuses, one for each pump.