Function Instruction of the Switches: 1.Turn Red and Green switches to both sides, pet is prevented from entering or exiting house. 2.Turn Red and Green switches to right side, pet is allowed to enter house, but prevent from exiting house. 3.Turn Red and Green switches to left side, pet is allowed to exit house but prevent from entering house. 4.Turn Red and Green switches to middle, pet can leave and exit any time. The Large Size: outer size: 9.25(w) x 9.92(H) x 2.16(D) Inner size: 7.08(W) x 7.48(H) Cut-Out Size: 7.7(W) x 8.3(H) Generally, average installation height is around 10-15 cm from the floor. Installation Notes: 1.There are total 8pcs screws, 4pcs used on the front and the rest used on back. 2.Generally, average installation height is around 10-15 cm from the floor. 3.If the cat flap door is too thick for the door you want to be fixed to, use a scissors, saw or cutting machine to cut along the line A or B as shown. The cutting scale is around 3 to 6 mm. For small cat flap door, the cutting scale is around 1 to 3 mm. Package Includes:1 X Large Cat flap door;8 X Screws;8 X Screw caps;1 X Installation instructions