The Power Pet Large Electronic Pet Door PX-2 is a motor driven vertically-sliding door that is activated by the MS-4 ultrasonic collar. The door is made of white and brown panels that are 12-1/4″ wide and 16-inches long for dogs up to 100 pounds. The door features a directional sensing system that opens the door only when the pet is on a direct approach, not when it is just walking by or sleeping next to the door. The door also has 4-way access control that allows you to select from In Only, Out Only, Full Access, or Closed & Locked. The door is wind and weatherproof with an airtight seal and features automatic deadbolt locking.