The Pet-Tek Glass Fitting Glass Fitting Multi-Magnetic Cat Door in White is an ingenious innovation that means you do not have to worry about letting unwanted animals into your home when you have a cat flap. It works through attaching a magnet to your cat's collar that the door recognises when your cat comes into close contact. The signal activates the door mechanism and your cat can enter. When your cat has passed through it the door will shut behind. As the system is controlled by magnets you do not get the problems associated with electronic systems and this model will perform year after year.The door is made from Bayer high impact polycarbonate the same material that is actually used for bullet-proof vests and aircraft windows! You can be sure that it will stand up to years of daily use. That is not all! It features a 4-way locking system so you can choose to let your cat in only out only travel in both directions or lock the flap completely to keep your cat inside. A useful feature we are sure you will agree.Please see below the useful features of this product: Fits max glass depth of 26mm The all New-Multi Magnetic System eliminates costly battery replacement and any electrical maintenance No more locked out pets due to battery failure. Helps keep stray cats out Made from Bayer high impact Polycarbonate and Lustran Plastics No maintenance 3 Year warranty Self lining door Fits glass also doubled glazed panels Stainless Steel screws (no rusting) Weather seal to reduce draughts Self closing magnetic location Four way locking system for manual use if requires - In Out In & Out and Locked UV stabilisedConsult a professional glazier for fitting.Pet-Tek Superior designed cat / dog doors are simple to install look great and will give you the peace of mind that your pet is secure. Renowned for their trouble free performance this product will endure years of regular use. Suitable for medium-sized cats Dimensions: 27cm diameter x D2.5cmDepth that protrudes from door: 9cm Flap size: W15 x H17cmCutout: 24.5cm diameter