These screws provide a rapid and effective light duty anchoring system for fixing into concrete, brick, stone, concrete block and wood. This through fixing provides a single solution and replaces traditional fixings such as nylon frame and hammer fixings.  Box of 100 screws, 7.5 x 100mm. 1 TX30 Driver Bit included with each pack. Designed to replace traditional masonry fixings TX30 TX Drive recess to reduce driver wear & prevent camming-out Serrated V-threads to achieve optimum insertion into all masonry types Zinc plated and yellow passivated for increased corrosion resistance High-Low thread on first 30mm to aid insertion and reduce torque Ideal for fitting windows and door frames Flat countersunk head with five locking ribs All steel, non-flammable fixing conforming to BS 7671 standard's 18th edition, which requires wiring systems to be supported by materials which are unlikely to prematurely collapse in the event of a fire.