We recently bought the 2-cat kit for our cats, Ollie & Pickles, who are brother & sister. Ollie had been very ill and kept inside for weeks until he recovered, so that's primarily why we bought the Tabcat, though we use it for both cats now. The Tabcat works brilliantly for locating both cats - but here's the thing: Ollie has got so used to it now, he even RESPONDS to the bleeper and comes home! This product is amazing for the purpose of knowing where your cat is - and the cat can even learn to respond very quickly, which is a bonus. Thanks so much for this innovative tracker that only requires a one-off payment. Kudos!