PetSafe Medium White Aluminum Pet Door for pets up to 40 lbs. Solid aluminum for durability and a locking panel for added security. The transparent single flap ensures a weather-tight seal, keeping your home comfortable and energy-efficient. Easy do-it-yourself installation makes it a breeze to set up. Suitable for doors from 3/8" to 2" thick, with a flap opening of 8-1/8" x 11-3/4" and a cut-out size of 8-7/8"W x 13-3/4"3/4"H.