Garage Doors Remotes
64LM Liftmaster Garage Door Mini Transmitter
The 64LM has been DISCONTINUEDA Proper replacement that will work for you will be one of these remotes:
http://www.justgaragedoorremotes.com/remotes/liftmaster/LiftMaster-890MAX-button-Mini-Garage-Door-Remote-Control-Opener_210?previous=