Brass Covers that fit over 5/16"unc/unf socket cap-head screws. They are designed to be lightly tapped onto the screw head, providing a permanent brass cover, allowing access to the hexagonal socket through a hole. Unfortunately, screw manufacturers do not all produce them with the exactly the same size heads. This means that on some they might have to be 'lightly tapped' a little harder, and on some they may just slide on and require a drop of Loctite. They are made from real brass, and transform an engine. SOLD IN BAGS OF 5 !!! Please email if you want to see a picture of them on an engine roy@billetbikebits.com