These forgefix mirror screws are zinc plated for resistance to corrosion and have a slotted screw head and a threaded female insert in the head and shank they have a chrome plated dome with a threaded machine screw type male insert and screw in top often used when fixing mirrors or signage the single threaded screws will hold firm in wall plugs applicationsuitable for use when fixing mirrors or signage in sanitary and similar locations zinc coatings prevent oxidation of the protected metal to cr