2 Quality Flap: Petcoming Plastic dog door comes with 2 pieces of excellent quality magnetic flap that can fluently close after your pet passes through the dog door. Compared to other dog doors with only 1 piece flap, our 2 flap is more windproof, waterproof and soundproof. Choose the Right Dog Door for Your Puppy: Measure your puppy's shoulder width and height according to the guideline in the picture to make sure your puppy can pass through this door. Medium Dog Door Flap opening measures 13.2'X7.9'. Suitable for pets weighing up to 45LB. Petcoming plastic dog door is suitable for doors or walls with a thickness of 1.02'-2.36', please make sure of the fitment before purchasing.