Thread Diameter 0.250" Head Diameter 0.477" Head Height 0.312" 82 Degree Countersink - Slotted Drive 18-8 Stainless Steel provides strength and offers good corrosion resistance in many environments. Oval heads have a low dome and are tapered for counterinking. Machine Screws are a straight shanked fastener designed to be used in a hole that is pre tapped or a clear hole with a nut on the opposite side. Stainless Steel Machine Screws are used in applications which require general atmospheric corrosion resistance, refridgeration quipment, and food processing machinery. These screws have an approximate Rockwell hardness of B85 - B95 and a minimum Tensile Strength of 80,000 PSI. Machine screws are often used with nuts but also often driven into tapped holes (without nuts). They might be considered a screw or a bolt based on the Machinery's Handbook distinction. In practice, they tend to be mostly available in smaller sizes and the smaller sizes are referred to as screws or less ambiguously as machine screws, although some kinds of machine screw can be referred to as stove bolts.