I was trying to find a way to simulate bolt heads when I stumbled across these. There are three sizes of bolt heads and nuts, and about 250 of each piece. You need to use a fresh knife blade to cut them off the plastic backing, and tweezers to handle them, but they're not difficult to use. And, boy do they look great!

Really great casting quality! The perfect size for my 1/25 scale semis that I build. Its take a little practice to get them off the backing without losing them, but you will figure it out.

these detail bits come flat on a sheet of plastic. unless you want to cut each bolt head off the carrier sheet about all I see this being good for is if you need a row of bolts at a time. plus, it looks more like rivet heads to me than bolt heads.