Fast-acting clamps are the workhorses of most woodworking shops, as they are easy to use, lightweight and quick to adjust. These clamps have a pair of clutch plates that release with a squeeze, allowing one jaw to slide freely. When tightened, the clutch plates ensure the moving jaw remains reliably in the position you set. Exerting a clamping force of up to 300 lb, they are available in three lengths (4", 6", 12" - 100, 150, 300mm), each with a 2" (50mm) throat depth, a 5/16" diameter steel screw and a 3/16" thick by 5/8" wide high-carbon steel bar. They have comfortable contoured plastic handles and come with removable plastic jaw liners to avoid marring your work.