Metal C-clamps are a multi-purpose clamp, with a lot of clamping pressure, that is used for myriad tasks around my woodworking shop. My C-clamps range from 3-inches up to 8-inches. My main uses for C-clamps are keeping panels flat during glue-ups, and for clamping table legs to a board in my vise, so I can securely chop mortises on the workbench surface. We use a lot of C-clamps in our woodworking school, especially when we’re making smaller tool projects, like Try Squares, Bench Hooks, Shooting Boards, etc. Guitar makers, violin makers, and other luthiers use a lot of C-clamps when they bend the frames of their instruments. C-clamps are pretty simple clamps, but can come with some features like a quick release button, which is quite convenient.