Hey guys! So I am most likely getting my bp next weekend! Anyways, I was wondering, which one of these UTH's is best for a 40 gallon breeder?

http://www.reptilebasics.com/ultrath...ater-uth-6-x11

or
http://www.reptilebasics.com/ultrath...ter-uth-11-x11 ?

Do i need a thermostat for these?
Thanks, Kat