DOOR OPENING: The Microchip Pet Door Flap opening is 6 11/16” (H) by 7” (W) and can be installed in doors, windows or walls – accessories are available from SureFlap. MICROCHIP COMPATIBILITY: Works with 9 (Avid Secure), 10 (FDXA) and 15 (FDXB) digit microchip numbers; if unsure of your pet’s microchip number, you can check with your veterinarian, pet shelter or animal rescue.
Cat door great, large cat/small dog door not so much
I had the small cat door and it worked great but it was a little too small for my cats and they didn't really like to go in and out. So I bought the large cat/small dog (next size up) door and installed it last fall. While my cats like to use it better, I have had several problems with it. It is not nearly insulated enough. When it was cold last winter, it had frost on the inside of the door flap. Then when I was on vacation in May 2019, I had raccoons in my house. They were able to ram the door hard enough to get in. I saw them do it after I got home. I actually had to barricade it at night with cement blocks until I could capture them in live cages. The whole reason I bought the chip door was to keep the raccoons out.