Transmitter Solutions 390LMD21K3 Remote Replaces the 390LMD21K. LiftMaster 61LM, 64LM Compatible One Button Key Chain 390MHz 9-Trinary (+ 0 -) Three Position Code Switch Type Garage Door Or Gate Opener Remote Control. Compatible With Chamberlain 750CB, 756CB And Sears Craftsman 139.53708, 139.53758. Works with LiftMaster, Chamberlain, Sears Craftsman code switch versions of garage door openers manufactured between 1984 and 1992 on the 390MHz frequency that use the trinary code switch remotes.