Polarity Reversing Relays
Power window motors, power trunk lifts, door locks, etc. need to reverse the direction of rotation of the motor in order to work. This is done by reversing the voltage polarity to the motor wire leads. Reversing relays are needed when you want to use a switch that doesn't automatically switch (reverse) both the positive and ground to the electric motor (such as a 3-wire switch or remote control).
ALSO when you want to use a remote control with a 5-wire, power window type switch, these relays will prevent the remote from shorting back through the 5-wire switch. Complete with 30 amp relays, wire leads.