You might want to post your enclosure dimensions and such and you will get an answer faster. I use a 75 for a 6 x 4 and it is not enough. I had to add a fan driven heater with a thermastat to compensate.
I've never heard of the brand but che are easy to make and last long.
but i agree with the previous advice. you don't need one unless you live in a refrigerator. your tortoise actually benefits from a night time drop in temp to the 60s but as said, they can survive lower. if you tort is too hot he will stop eating and likely bury himself all the time. i had that problem because i had my Russian enclosure on top of my leopards enclosure and the heat rose and my Russian was very unhappy.