Available here are Clutch Head Round Security Self Tapping Screws. The clutch head is the original one-way security drive. The special ridged design of this drive means that it can only operate in a clockwise motion. Installed using standard slotted screwdriver - no specialist tools required. These are manufactured from A2 Stainless Steel. We do also stock this item in Case Hardened Steel with a Zinc Plated (CR-3) Finish. This item is sold in a box quantity of 100.Please allow 3 to 5 working days for delivery.