You are purchasing the Liftmaster 971LM 390mhz Security Plus (p/n: 971LM 390mhz Security Plus) Garage Door Opener guaranteed replacement for Craftsman 139.53681b (p/n: 139.53681b) Garage Door Opener Compatible Device Type: Liftmaster 971lm garage door opener. Features and Specifications 1 channel/button transmitter, compatible with models manufactured from 1997-present 390 MHZ Frequency, over 100 billion codes with code rotating technology (Security+) Orange/Amber Color LED LIGHT on back of motor Visor clip and Lithium battery (5 years life w/normal use) included Compatible with ALL Security+ systems, including Chamberlain, Sears, Craftsman and Raynor code rolling residential openers.