These star-headed cast iron effect soil fixings are an optional alternative to standard screws. With their cast iron effect heads they really do complement the wide fixing lugs and oversized sockets of the cast iron effect soil system. They require a 12 point socket to tighten them. When using these fixings on Ogee and Rectangular hoppers, we would recommend using a 3/4andquot; tap washer. When fixing to concrete, bricks or blocks you should fix them using the same method as any other screw by using a plug type fixing and when fixing to timber, a pilot hole should be drilled first. This is constructed from a durable metal. It's ideal for a range of domestic DIY applications.