Clamp styles include C-clamps, bar clamps, pipe clamps, deep-throat bar clamp, one-handed bar clamps, spring clamp, ratchet-action band clamp, mitre clamp, and hand screws. Bar clamps have adjustable arms that are easily widened or narrowed to fit the workpiece and, therefore, requires fewer turns of the screw spindle, compared to a C-clamp, to hold the piece tightly. http://www.workprotool.com/hand-tools/mechanics-tools/ratchet-handle/