The High Tech Pet Power Pet Medium Electronic Pet Door PX-1 is a motor driven vertically-sliding door that is activated by the MS-4 ultrasonic collar. 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 a 4-way access control that allows you to select from In Only, Out Only, Full Access or Closed & Locked. The door is made of high-quality materials and is designed to be durable and weatherproof. The door also features an automatic deadbolt locking system that adds a level of security above any other pet door.