ok, i no the hole girth thing. but i have a question about rat size anyways. i buy weaned rats for rex at a store and i measured them and there about 3in long. i looked on rodentpro.com and says that weaned is 3.5-4.5 so i think thier pups and not weaned. my question is, rex is about 20-23 in long, what size rat should he be on? thanks for the answers, i know, its a dumb question, but hey, im still somewhat new at this :wink: