The Catwalk® Glass Fitting Maxi Dual Glaze pet door is designed for glass panels from (3mm – 28mm) in thickness, and makes it suitable for single and double glazing applications. Flap size: 195mm x 185mm Overall size: 304mm diameter Application: Glass fitting (3mm – 28mm) Pet size: Large cats and small dogs (see breeds below) Cut out size: 267mm diameter For sliding doors: The G-SDDC protrudes 17mm on the inside and 11mm on the outside of the door its connected to. Please ensure enough clearance for sliding doors to pass the pet door. Please note: the pet door cannot be installed into an existing tempered glass or double glazed window. The glass panel would need to be replaced with the hole already cut at time of manufacture for the pet door to be installed. Please note the sizes below are recommendations only, and we always recommend to measure your pet first and contact us if you are unsure. Large cats: Maine Coon, Savannah, Ragdoll, Chausie, Ragamuffin, Siberian Cat, British Shorthair, Highlander, Turkish Van, British Longhair Small dogs: Yorkshire Terrier, Shih Tzu, Chihuahua, Pug, Pomeranian, Miniature Pinscher, Cavalier King Charles Spaniel, Papillion, Maltese, Bichon Frise, Beagle