Smart start protects electric motors against low voltage starting. Manufactured in the USA with worldwide patent. This product reduces starting amps draw by 30-40%. The principle is it unloads the cylinder heads so that the compressor pump is not pumping on startup therefore, preventing the enormous amps draw which causes damage to switch gear and capacitors in the electric motors, with compressors having to start up under load with normal fliters. Will fit most common air compressors.