Liftmaster 485LM Battery Backup for Liftmaster 3850 Opener
MODEL 485LM EverCharge Integrated Standby Power System For use exclusively with the LiftMaster model 3850 garage door opener Operates the garage door opener as if the power was still on (all safety and security features still operate) Standby Power System and opener are one logic board, resulting in better performance in Standby Power mode Improved Battery Recovery System.