What size is my flexwatt supposed to be for my ball python?

im getting a baby ball python soon and im gonna keep her in a 28 quart tub. i heard flexwatt is the best for tub and i tryed looking for stores in scarbrough but couldnt find exept online and i found 2 websites and they both r diffrent on has same size but diffrent volts and the other is diffrent im confuesed so can someone go on both websites and say which one is better from both and which one is right for a baby ball python for a 28 quart tub??

also when it grows bigger im gonna get a 44 quart tub and it will be big so for tat also which one will be right

websites:

http://beanfarm.com/index.php?cPath=1204

http://www.reptilebasics.com/heat-tape


thanks

I'd go with the 4" THG tape from Reptile Basics.