Stinger 81LM is a replacement for the now discontinued Liftmaster 81LM and all sears craftsman 139 model numbers listed above. It is compatible with operators manufactured between 1993-1997 and uses a "Smart" coding button with a Green LED light that will light up when you press the smart button on the back of the overhead motor to program the remote. The STINGER 81LM is a 1 channel transmitter, compatible with the "Billion Code" series. It includes a visor clip and Lithium battery (5 years life with normal use), also instructions come with the remote.