For metric and imperial nuts and screws with widths across flats from 10 to 32 mm (3/8" up to 1 1/4"); self-locking from 17 mm: no slipping on the workpiece zero-backlash gripping of metric or imperial hexagonal headed screws, no rounding of bolt heads, reliable and tight gripping of rounded, rusty, or thick coated bolts and screws ideal for work on vehicle brake systems, quick tightening of bolted connections using ratchet action, push the button for adjustment on the workpiece, also possible with one hand only fine adjustment for optimum adaptation to different sizes of work pieces and a comfortable handle width, box-joint design: high stability due to double guide, reliable catching of the hinge bolt: no unintentional shifting favorable lever action: optimum transmission of force, guard prevents operators fingers being pinched, replaces a set of wrenches, ideal for tightening locknuts, Chrome vanadium electric steel, forged, oil-hardened