Grips rounded fasteners up to 5X better Fits both inch and metric fasteners Movable jaws grip onto rounded fasteners Box end equipped with locking cam 5 piece wrench set fits the following sizes: 3/8inches and 1 mm; 7/16inches and 11 mm; 1/2inches and 12 mm, 13mm; 9/16inches and 14 mm; 5/8inches and 15 mm, 16 mm Full Lifetime Warranty, refer to "Warranty & Support" section below for full details