These Forgefix Rimmed Expansion Wall Plugs are made from 100 Nylon They rest on the surface of the base material and are particularly useful when the depth of the base material is not known Sprung anti-spin fins provide a two-way lock preventing spinning and loosening from overhead applications Due to the precise two-way expansion the plugs are suitable for close to edge applications APPLICATION Ideal for both lightweight and medium-duty fixing applications Often used for satellite dish installation Suitable for all types of threaded screws including multi-purpose general purpose coach screws etc Not suitable for machine screw threads