Petsafe Staywell Original 2 Way Pet Door Mixed, , Petsafe Original 2 Way Small Pet Door. White Barrier locking system|Overall size: 236 mm x 198 mm (91/4" x 73/4")|Cut out size: 185 mm x 158 mm (71/4" x 61/4")|Maximum pet shoulder width: 147mm (53/4")|Maximum pet weight: 7 kg (15 lbs) - cats and small dogs