Stahlwille Series 40D Bi-Hexagon sockets with 1/4in Square Drive in metric sizes are made from HPQ® high performance steel, and are chrome plated. HPQ® sockets are manufactured from selected tough steel alloys for an extremely high load capacity with exceptionally thin rings and walls. They are free of cadmium and are therefore suitable for use on titanium alloy parts and titanium fasteners, such as those used in the aerospace industry, where safety is a crucial factor. The Sockets are equipped with AS drives to permit high transmission of forces to the lands of the nuts and bolts without damaging them. Manufactured to DIN 3124/ISO 2725-1. MADE IN GERMANY.