By incorporating one of these boxes, the possibility of voltage drop will be eliminated and the actuator will be supplied with a full 12 volts of current at all times, regardless of the length and age of the power supply wires. This will insure that your actuator will operate at its maximum speed. The relay box incorporates two relays that are encapsulated in epoxy for corrosion resistance. The relay box also allows the use of a single pole switch to operate reverse polarity actuators and can accommodate two actuators simultaneously. NOTE: ALL SALES ARE FINAL ON ELECTRIC PARTS - NO RETURNS, REFUNDS, OR EXCHANGES.