Our high performance screw line includes machine screws with countersunk zinc metal threads. designed to screw straight into a threaded component or to be used in conjunction with a nut and washer for a \”bolted\” connection. Door furniture, fixtures, bracketry, sheet metal, and other common engineering and construction components can be securely but easily fastened to wood, metal, plastics, or any other material having an internal thread or drill hole using a smooth under-head countersink. Panhead design is also an option. made from 4.6 grade steel and protected from corrosion by a bright zinc plate coating.