Replacement Battery for Liftmaster 8550 485LM Battery and 41A6357-1 battery-works with Liftmaster 3850 Beiter DC Power BEITER DC POWER BRAND Operates the garage door opener as if the power was still on (all safety and security features still operate) Arrives charged. Works out of the packaging. Remove terminal protectors before installation. 100% rechargable. Service life of 3-5 years. 12-Month Warranty, 30-Day Money Back Guarantee top the beeping now! Order today! Don't pay for a service call, simply unplug old battery and install new battery. It's as simple as that.