All our efforts have to date made us one of the biggest internationally operative tool manufacturers with customers in over 135 countries of the world. Precision straight edge, 300mm This construction style is far superior in strength as well as the maintenance of exact torque length. All of SK's interchangeable heads are made from a single piece of alloy steel. The dovetail design provides an exceptionally strong connection and allows for complete head interchange-ability across the full spectrum of torque ranges.