Product description
Machine screws are measured like other screws: For flat heads, length is measured from the top of the head to the tip of the thread; measure oval heads from the edge where the dome top meets the sloping bearing surface to the threaded tip; all other machine screw head styles (Binding, Fillister, Hex and Hex Washer, Pan, Round and Truss) are measured from under the head to the screw's tip. Length is specified in fractional inches.
Use machine screw flat washers to increase the bearing surface of the screw's head or nut, which can be useful when working with soft materials and oversized or irregular shaped holes.