Chamberlain Liftmaster 485LM Battery LiftMaster Garage Door Openers 485LM Battery Backup, OEM Allows you to still come & go through your garage door, when the power goes out Lift master 485lm battery backup system - chamberlain part number 4228- 100% OEM New production dates- LiftMaster factory supplied Also works with sears and home depot garage door battery back ups- replacement part Compatibility for all battery back up units with slide in battery - 385/855 and new models