Be careful if you have very large cats
I have used these for about 6 years, have 4 cats & 3 feeders, they are all on different diets. One will eat nothing but biscuits - sadly. One on a renal diet, one on a normal elderly diet & have just rescued a skip diver, counter surfer dustbin cat.
My Maine coon cannot use his properly. He has a very long neck & because his microchip is between his shoulder blades, it won't recognise it until his head is out the other side of the arch. It then opens & he panics running off with it around his neck. I could use the rfd tag, but, he has never had a collar & feeding him on the hall windowsill at the top of the stairs that only he can reach, seemed an easier option. They are rather large & tricky to clean, especially if your cat eats like a rotavator! Very good item that does save you money as less waste from spoiled food.