Your choice Large 12"x 16" or Small 8"x 9 1/2"  All you do is snap the two halves on the door over the screen, press together and cut the screen at the sides and bottom of the door. It can be used on any type of screen, nylon, aluminum and can be secured with the built in latch to prevent access. Very user friendly. 

Small pet door is the perfect size to install on a window screen for easy access for your cat.

Give your pet the freedom it deserves and stop the scratching on the screen itself, plus you won't have to miss out on what you're doing. Our dog insisted on making his own hole before we installed this miracle.