This tool is for hexagon socket screws manufactured with an internal pin. This drive prevents removal with standard hexagon tools. Suitable for medium torque applications and is one the most difficult to remove without the matching driver. We have a full range of AB Self Tapping and Metric Machine Screws stocked in A2 Stainless Steel. This item is sold in singles.This is not a stock item therefore please allow 3-5 working days for dispatch. As this is not kept as a stock item, this is non-returnable. M3.5 Hex Pin Security Drill Bit 25mm Length - A2 ST ST