they work great....I used racks for years from PM Herp...Paul is a great guy too....I can't remember any snake escaping that was not my fault.....(holes too big )...

they don't supply heat due to the American habit of suing people when products fail....no matter who's fault it actually was....
I used no heat...but I heated the whole room....

.....I would say Flex-Watt 3" down the back...but I never did it so it's just a thought....>
-----
........JY