uth matts on metal surface

[MrPower]

Hello fellow reptile keepers. I am stumped here. I have a large custom enclosure that was used for an adult iguana. Now I have renovated it for my red tail boa. I just purchased an under tank heat Matt for under the hide as do all my snakes But I never really thought of the fact the bottom is a metal tray. Now the Matt's state for glass use oblue. But I can't find anywhere on Google Why They could not be used on a metal bottom. I'm assuming the metal gets hotter then glass or something. Anybody have some knowledge on the subject for me, Thanks for reading all.