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.