Available here are Armour Ring fasteners in Case Hardened Steel in Zinc Plated (CR-3) Finish. A simple conical collar which renders a standard hexagon nut or bolt tamper resistant. The Armour Ring can be applied to any British or DIN standard hexagon nuts or bolts using a standard hammer. It leaves a smooth clean finish which is often favoured by Health & Safety executives and isn't governed by a torque level like some one-way fasteners. These have been approved by the Home Office. This item is sold in a box quantity of 100. 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. Click Here to view installation video. M6 Hafren Armour Ring - Steel Zinc Plated - Box of 100