These are a nightmare to get hold of..... :roll:
the trouble is that they get thrown out with the flooring and then lost forever. They have an opposite thread on them which I've tried to get my local engineering company to replicate as I was going to sell them in the Baydreamers shop, however they didn't have a tap and die wotsit thingy that matched.... :?
good luck in your search, I'll keep an eye out for one... :wink: