Stinger 81LM is a replacement for the now discontinued Liftmaster 81LM and some of the sears craftsman 139 model numbers. It is compatible with operators manufactured between 1993-1997 and uses a green smart button on the back of the overhead motor to program the remote. The STINGER 2 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. The wireless keypad that is compatible with this Sears Craftsman garage door opener is the 387LM universal keypad. this is the new and improved design by transmitter solutions.