What types of doors or windows can I install this on?
You can install it on wood, metal, plastic, glass (needs a glass cutter), or rigid wire mesh.
My cutout size of the cat door isn't perfect. Is that okay?
Yes. As long as the hole is smaller than the outer frame and larger than the inner frame, the cat door will fit.
What should I do if the cat door flap won't close properly?
The rotation shaft (on the top of the flap) might need smoothing. Simply remove the flap by holding one side and pushing the other side out, then gently smooth the shaft with a knife.
My pet can't push the flap open. What can I do?
Make sure the lock is set correctly and the flap is straight. If stiff when pushing, smooth the hinge pin (see Q3). If moving fine but pet struggles, check if the brush seal is blocking the way.