I have been housing snakes (balls, carpets, and boas) in racks for around six years, and have never had one of them slide their tubs out. The tubs in my racks are pretty snug, though. I have had one escape from a rack though. Someone did not close the tub all the way in a baby rack, and it got out a few minutes later. Luckily, I was in the other room, and heard it in the act.