Namsan Cat Flap Pet Screen Door Lockable Magnetic Cat door Easy Install Durable Door for Cats Dogs(8" W x 10.2" H)

TLDR: Don't be lazy. Take your screen off and install it on a table.The principle is simple enough: you affix it to your your screen by sandwiching the outer and the inner frames together with bolts and nuts, then cut a hole to your screen, and finally pop in the flap door. Sounds simple enough, therefore I didn't take off my already fixed screen.Big regret time: The bolts are flat and chunky and will not pierce into the screen. I had to mark the positions with a marker pen and cut holes with a tiny scissors. My holes are not aligned well because I am crouching down and trying to get hold of the already fixed screen with one hand, while the other hand is trying to keep the frame in the right place. When the frames are finally sandwiched together, the screen is ragged so the frame halves will not stay flush. I pressed on and cut the hole out of it, again didn't do a good job and there is still some screen sticking out of the frame. When the door is finally put in, it does flap both sides but because there are bits of the screen sticking out there is obviously more resistance. Although doing a less than satisfactory job, my cat nonetheless has no problem using it.

Absolutely brilliant product. Really simple and easy to follow instructions, good size for our small dogs and is really durable. Our dogs love the freedom of being able to come and go as they please, and the doors looks good!

This item is not a dog flap for use on a normal timber door, it is for an internal fly screen, hence when fitted it is not sealed to the elements, it is a plastic flap with MESH paw prints. totally useless.

Easy to fit with a little DIY knowledge