5/16-18 x 2-1/2" Phillips Truss Head Machine Screws Stainless Steel 18-8 Qty 100A Truss head screw has a head with flat underside and a slightly domed top. It has almost no exposed edge. Machine Screws have with "machine" threads for use with a nut or in a tapped hole. Also referred to as a stove bolt. General Product InformationHead Style : TrussDrive Style : PhillipsDrive Size : #4Thread Size : 5/16-18Length : 2-1/2"Material : Quantity of Fasteners in Package : 100Detailed Product Information:Head Diameter : Head Height : 0. 183"Thread Diameter : 0. 3125"Threads Per Inch (TPI) : 18Coarse or Fine Thread : COARSEThread Coverage : Full ThreadThread Length : 2. 5""Key Notes:Machine screws are uniformly threaded screws of 1/4" nominal diameter or less that is designed to be threaded into uniformly threaded nuts or threaded holes in the parts they are intended to fasten. Machine screws primary tightening is accomplished by turning the head of the screw. With a bolt, the primary tightening procedure might be accomplished by turning the nut. Truss heads have very wide and low profile that gives a clean appearance as well as offering a much larger than most surface area that is required for applications where there is a risk of a screw head pulling through a pilot hole. Phillips drive is a cross head design and is the most commonly used type in America. Phillips is often criticized for its tendency to cam out at lower torque levels but this was actually a deliberate feature of the design, for the purpose of assembling aluminum aircraft without overtightening the fasteners. The vast majority of stainless steel fasteners are produced with metals from the austenitic family. Their high levels of chromium and nickel provide tough corrosion resistance and the ability to withstand considerable physical strain