You do realise that they come as standard with the reels concerned? The only reason that Mike has had to lash out a whole two quid is because they aren't provided when you buy an aftermarket spare spool.
My post mentioning shallow spools was no more than a little tongue in cheek reply to dorsetsteve last post. I really couldn't care less about spool reduces, shallow spools or indeed spools that are too deep. My reels are filled to just the right depth with backing lines to accommodate the exact amount of lines I use in the breaking strains I use.