Chose this model because I was upgrading from a lower spec Cat Mate and the hole dimensions are not so far apart. Liked the fact it works solely on batteries and doesn't have a porch sticking out to catch your legs on. Took about 2 hours to program 5 cats and install in my steel clad garage personnel door. It does make an audible clunk when the latch triggers but this didn't seem to deter my cats and even my little feral girl was in and out within a couple of hours. Thus far I'm very pleased, it has cost me the same price as a trip to the vet to patch up a lacerated moggie and should help avoid any more such trips. Peace reigns once more in my garage!