Hi, thanks for the question. Yes they’ll work on most cages, apart from the newest ones (which are actually our favourite) that have the drum type lock built in. But any that take padlocks will work with a plastic tab thing. I think that the numbers are embossed into them so can’t wash off, but can’t be sure. We got some free with early cages we bought but have only ever used them for going through airport security.
For lockboxes a friend of ours used a ‘kitchen lock box timer’ from Amazon, seemed to work well. I think they’re designed for putting snacks in when you don’t have enough self control not to eat them, so, similar use really 😛