catlog home First Generation: 1, Second Generation: 1 catlog Genuine: 2 All scrunchies are size M, genuine. The detection accuracy improved when using two devices. I've used the longest one for about 3 years. There is some wear and tear, but I've taken good care of them, so I think they are still in good condition. However, they are not new, so please understand. You can start using them immediately by registering the devices with the app. I changed them depending on my mood, but they can also be used by those with multiple cats.