cage help!!

ok guys so heres the deal. im trying to decide between an AP or boaphile cage for my hog isle. i have read that ultratherm heat pads are good to use for both and that they dont neccesarily need a thermostat as they use low wattage keeping their top heats down unlike flexwatt (granted you always want one just to be safe). being the concerned parent i like the idea of a thermostat failure not hurting the snake. does anyone have any experience with the ultratherms or anything similar to them?
if so what size would i need for a 421d boaphile or a T8 AP cage?

I've had a few Ultratherms, and they're good heat mats. They can still get pretty significantly hot under the right conditions (on a solid surface with a decent layer of bedding), so I wouldn't go without a thermostat, but still not near as bad as I've seen with ZooMed heat pads. With the Ultratherms, I've even had the issue of it not getting hot enough--in that case, I had it on a wire shelf, so no solid surface beneath to hold the heat in, so all that warmth was dissipating before it could penetrate the tub.

If I'm not mistaken, you can order either of those with the proper sized heat. Not sure if it comes "pre-installed" as I haven't purchased from either company, but it would at least take the guesswork out of figuring out what is the right size.

Not trying to sway your choices in cages but.. How soon are you looking to get the cage? Boaphile had very poor customer service when I tried contacting them, and I have heard that it takes months for their cages to be shipped and built. I went with showcase cages for my snakes, but if you're not looking for anything fancy, have you looked into vision cages at all? But if it was between boaphile and animal plastics, I'd go with the animal plastics. There's also some concern with the building materials that boaphile uses with the potential to release toxins. Sorry I can't help out with the ultratherm question