Countersunk Socket Screws feature a countersunk head type, which allows them to sit flush with their target housing. Countersunk screws are designed to be used alongside pre-drilled countersunk recesses. Driven by a hexagon wrench/Allen key. Countersunk head gives a flush finish once in place. Conforms to DIN7991. Grade 10.9 Steel. Bright Zinc Plate (BZP) finish offers resistance to corrosion.