Cup square, non hex, black japan, GR 4.8, STD, 8 x 1.25 x 65 mm, Fastbolt.

Cup square bolts are primarily used in construction. Being useful for connecting metal and wood, they are often used when securing corrugated sheets onto various structures such as houses, car ports, and patio roofs. The cup square bolt itself features a spiral shank for extra grip when it is screwed in. this makes for an effective combination with the seal, which is knocked into place to provide effective waterproofing. Black Japan is a lacquer or varnish suitable for many substrates but known especially for its use on iron and steel. Its high bitumen content provides a protective finish that is durable and dries quickly.