Large Power Pet Door in Clamshell Packaging. Engineered for performance, design, value and extreme reliability, Power Pet doors are motor driven and activated by a tiny ultrasonic collar. Other electronic pet doors merely unlock a hinged panel, requiring your pet to push it open. That's something that a lot of pets don't like to do. Patented Power Pet doors open completely under their own power. They feature a translucent door panel made of a new super-strength resin. When your pet approaches, the air-tight panel quickly and quietly powers upward, disappearing into the stylish housing. Because the panel moves up and down and does not swing out, it can be mounted in hermetically sealed grooves for air-tight closure. This mounting arrangement makes it impossible for an intruder to kick it out. An automatic dead-bolt locking feature adds a higher level of security to your home. The result is the most secure pet door against intruders and stray animals. Your pets are empowered to come and go as they please. Their animal friends are politely asked to stay out. Power Pet doors are completely wind and weather-proof with an air-tight sealing system. Power Pet's directional sensing system is pretty amazing as well. The digitally coded signal emitted from your pet's ultrasonic transmitter collar allows the Power Pet to work almost like magic, opening only when your pet is on a direct approach. 4-way access control lets you select from In Only, Out Only, Full Access or Closed and Locked. Dual range controls let you set independent inside and outside activation distances. Panel size: 12-1/4 by 16-in. for dogs up to 90-pounds. Operates on AC adapter (included). Optional backup battery (model B12V-1.3) snaps into the battery compartment to keep your Power Pet door functioning in the case of a power outage, or if you prefer to operate solely on battery power. Door is also operated by Humane Contain RX-10 multi-function collar for X-10 dog fence system.