we have a nock off, have had it for 5 yrs and it is still very comfy it is warm ,but put a thick matt.pad on it .no more heat, We also have a twin tempur pedic mattress it is to thin, not thick enough to support your hips with the conture of your shoulders your hips are heaver than your top . ,the nock off is 14inches thick , They say beware of the tempur- pedic it wares out fast (it gets soft). The grand kids used to fight over who slept in the twin. Dottie Bug