This Safety 4-Way Security Flap Door Locks are the ideal tools to help prevent unwanted pets from entering or exiting your house

4 Way Locking:

Turn Red and Green switches to both sides, a pet is prevented from entering or exiting the house
Turn Red and Green switches to the right side, a pet is allowed to enter the house but prevent from exiting the house.
Turn Red and Green switches to the left side, a pet is allowed to exit the house but prevent from entering the house.
Turn Red and Green switches to the middle, pet can leave and exit any time

Outer Door Frame Size :
Small: 20*19*2cm
Middle: 20*19*5.5cm
Large: 25*23.5*5.5cm

Inner Door Frame Size
Small: 16*15.7cm
Middle: 16*15.7cm
Large: 19*18cm

Note: Size S is a little different from other sizes. It's "thinner".