To ensure your pet’s safety, regularly check all kennel parts and doors for replacement. This Replacement Door is designed specifically for use with the Aspen Pet Pet Porter & Pet Porter II, Ultra Vari Kennel, Sky Kennel Ultra, Ruffmaxx Kennels, and the Petco Premium 500-800 series kennels, in sizes medium (28″ x 20.5″ x 21.5″), intermediate (32″ x 22.5″ x 24″), large (36″ x 25″ x 27″) and x-large (40″ x 27″ x 30″). To ensure a proper fit, be sure to match your pet’s kennel size with the appropriate product/item number for this replacement door.