Clutch Head Permanent Fixing Security Screws are also called Anti-Vandal Screws. Countersunk Head. Designed to be installed using a conventional screwdriver. The head of the screw has a normal drive face and a chamfered rear face, which prevents the screwdriver gaining any purchase when trying to undo the screws. Once installed therefore these screws will typically have to be drilled out to remove them. Bright Zinc Plate