High Tech Large Pet Fully Automatic Pet Door in Clamshell Package Motor driven vertically-sliding door is activated by MS-4 ultrasonic collar Directional sensing system opens the door only when your pet is on a direct approach, not when he is just wandering by or sleeping next to the door 4-way access control lets you select from In Only, Out Only, Full Access or Closed & Locked Wind and weatherproof with airtight seal; automatic deadbolt locking adds a level of security higher than any other pet door Panel size: 12-1/4 by 16-inches for pets up to 100-pounds