best heat pad for ball python??

[boa+python]

I was wondering what brand of heat pad is the best for a ball python. I am thinking of getting a t-rex cobra heat pad. There are other cheaper ones but have heard that this is the best. Are cheap heat pads as good as semi expensive heat pads, or is it just the name brand? Any info will be greatly appreciated. If you have a favorite/best heat pad please give me the name/brand/etc... THANKS!!!