Garage Door Opener Battery for LiftMaster & Chamberlain +485LM LiftMaster EverCharge Battery Power Supply 8550 3840 8360 3850 WD962KEV LW5000EVE. +The 485LM EverCharge Integrated Standby Power System for use with the LiftMaster model 3840, 3850, 8550 and 8360 garage door openers. +Also compatible with Chamberlain model WD962KEV and LW5000EV. +The 485LM operates the garage door opener as if the power was still on. Allows you to still come and go through your home's primary access point, your garage door when the power goes out. +Battery lasts uncharged for 72 Hours incase of a power failure