These solenoids are required in modified and outlaw drag racing as the stock foot plunger switches just can't handle the power!There have been zero reported failures of the solenoids! Designed for up to 24v use and up to 150 amps constant, 300 amp surge. The copper studs get the positive motor wire and battery lead.  The smaller studs are for the foot pedal and negative battery lead.

See wiring diagram in photos