Mark is right, if rodents have an exposed corner to chew, they will and eventually will chew a way out. The cat box and mortar tubs are smooth surfaced with no spot for them to chew on.
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Thanks,

Dave Colling

www.rainbows-r-us-reptiles.com

0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)

LOL, to many snakes to list, last count (05/26/2009):
36.51 BRB
29.42 BCI
And those are only the breeders

lots.lots.lots feeder mice and rats