Poss useful? They even have Winter Warmer stuff, I dunno if its any good?
http://www.planet-knox.com/SearchResult_sale.aspx?CategoryID=26
never had a back protector till last summer after a mate had a massive off, i brought knox one and had a spill in france, best 90 sheets i have ever spent, the back is proper scuffed just in the smae place my back would have hit the ground