1. quality material: The PET flap is made of ABS material with a smooth surface, ensuring exceptional strength and quality. 2. PET cat and dog flap size: Available in 3 sizes to suit your pet's needs. Large: Outer dimensions: 25 x 23.5 x 5.3 cm (H x W x D), inner dimensions: 19 x 18.2 cm (H x W). Medium: Outer dimensions: 19.7 x 19 x 5.3 cm (H x W x D), inner dimensions: 15 x 15 cm (H x W). Small: Outer dimensions: 19.7 x 19 x 2 cm (H x W x D), inner dimensions: 15 x 15 cm (H x W). 3. 4way lock: The cat door features a 4mode locking system. Adjust the red and green labeled switches to set the door to allow entry one way, exit one way, or remain fully locked. It provides flexibility to keep pets in or out while giving them the freedom to come and go without disturbing you. 4. Thoughtful design with transparent visibility: The clear flap allows pets to see through the door, which most pets prefer. The outer cover is waterproof, and brush strips minimize noise when the door closes, ensuring a peaceful environment for both pets and owners.