The 475LM Battery Backup System for your Liftmaster Garage door opener (see models below)
Works with LiftMaster: 8500 models 2500 3500, 3900, 3950 and 3800 garage door openers
This device operates the garage door opener as if the power was still on (all safety and security features still operate)
Audible signal sounds when door is moving under battery power
Bright LED lights let you know when the EverCharge is charging in use or when the batteries need to be replaced
