High Tech Pet CRG-12V-2 Charger Kit with 2 Backup Batteries for Power Pet Doors External charger kit with 2 backup batteries for Power Pet electronic pet doors Lets you operate your Power Pet door without an AC wall connection Keep one battery in use and one fully charged at all times, so your door is never without power Charge time is about 4 hours Complete kit includes charger, AC adapter and 2 rechargeable batteries