The Auto-Changeover LP Regulator allows you to hook up 2 Propane tanks and the regulator automatically switches over to the second tank once the first one runs out (and vice versa). The indicator changes color to let you know when a tank has been depleted and needs to be refilled. The inlet is a 1/4' SAE inverted flare and the outlet is a 3/8' NPT female. Also included are 2 of the 12' pigtails to connect the regulator to the propane tank or propane supply.