This self-contained unit has everything it needs to provide a safe, reliable, and worry-free 12-volt on-board air solution. It comes complete with a safety blowoff valve, drain cock, pressure switch, and a compression fitting making this unit the perfect air source solution for lightweight and compact applications. The HornBlasters Air Source unit comes completely pre-plumbed and pre-wired saving you time and energy. All you need to do is supply power and the unit automatically builds up PSI and turns off. When your PSI drops to much the compressor will kit back on and recharge your air supply. Note: Tank mounted air compressors are not fully sealed. For this reason, the manufacturer recommends the tank/compressor system be mounted in the upright position in an enclosed space away from moisture, dirt, debris, etc.