Let's say you removed a radiator for a spot of painting and then when you put it back a week or so later you noticed the bleed screw was missing, where would you get another one? Would a DIY shed like B&Q have them or would you need to go to a plumbers merchants? If you could also imagine it's Christmas Eve so you don't really want to be chasing around any more than you have to. I could be in for a frosty[1] Christmas dinner otherwise. [1] YKWIM