The Gearwrench combination ratcheting wrenches feature a 5 degree ratcheting arc vs. 30 degree on a standard combination wrench increasing productivity. The wrenches feature off-corner loading for better grip and reduced fastener rounding. The wrenches have a sleek head design allowing access to tight spots where a ratchet would not fit. The flexible head allows greater access to the most hard to reach fasteners. Adjustable set screw allows you to set desired head tension with spring washer design providing continuous head tension.The 9901D is a 12 piece flex head set in metric.