Proto® Tether-Ready 3/8" & 1/2" Drive 10 Piece Metric Hex Bit Set Includes 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm, 14mm and 17mm. Comes complete in sealed plastic box. Premium USA quality. Proto® Tethered Tool Sockets are manufactured with four detent holes so that the pin detent will engage correctly regardless of the direction the socket is placed on the square drive The Positive Control System requires a separate tool to attach or remove the socket, meaning it cannot be removed without specific intentChrome finish is applied after the holes are bored for better corrosion resistance Please See additional Pictures Below the Description.