The LiftMaster model 312HM is a single channel radio receiver that can operate on 12 volts DC or 18 to 30 volts AC and is ideal for commercial or gate opener applications. This LiftMaster 312HM radio receiver is compatible with the newer 315Mhz frequency versions of remotes controls by LiftMaster, Chamberlain and Sears Craftsman listed above. The LiftMaster 312HM receiver has more flexibility over other receivers by allowing it to accept a combination of 315Mhz remote types in the normal security mode or for maximum security only security+ remotes in the high security mode. With the normal security mode it can accept any combination up to a maximum of 31 of the security+ or code switch remotes. When set to the high security mode it can accept up to a maximum of 15 security+ remotes. The relay output of the receiver is an isolated dry contact rated at 5 amps and can be set to provide a momentary 1/4 second pulse or maintained contact while the remote is sending a signal, which is selected by an internal jumper. Having an F-connector type antenna allows for the antenna to be remotely located from the receiver using the optional 86LM remote antenna kit (sold separately) to obtain maximum receiver range especially when if the receiver is located inside a metal enclosure that would block the signal. An optional power adaptor LiftMaster 85LM (sold separately) can be used if the receivers required operating power is not readily available. The LiftMaster 312HM receiver controls one door or gate opener. This item is new in box and includes approximately 20 feet connecting wire, 8 inch whip antenna and installation/programming instructions.