While many electronic pet doors merely unlock the hinged pet door, the High Tech Pet Products PX Power Pet Door both unlocks and quietly powers upward, disappearing into the housing. This creates airtight closure, and when combined with the automatic deadbolt feature, a secure one, too. Plus, a digitally coded signal emitted from the included ultrasonic transmitter collar opens only for your pet, not stray animals. Use the access control to select in-only, out-only, full access, and locked settings as needed. An AC adapter is included, and the pet door can operate for months on one lithium battery (not included). In your choice of size.