PICTURES ARE REPRESENTATIVE OF ITEM, BUT ARE NOT OF THE ACTUAL ITEM. Product dimensions, finish, head markings, thread length, stamping shape or forging shape, etc., may differ from picture. Products are guaranteed to meet the specifications to which they are manufactured. Specifications allow for tolerances in dimension and shape, which can vary from lot to lot. The “Small Pan” head machine screw per JIS-B1111 is a preferred design for use in small electronic components where there is limited clearance area. The M3 and M4 diameters also meet the requirements of SN 213307 Cheese head screws. . Class 4.8 machine screws shall be made from a carbon steel, partially or fully annealed as required, which conforms to the following chemical composition-- Carbon: 0.55% maximum; Phosphorus: 0.05% maximum; Sulfur: 0.06% maximum. . Rockwell B 71 - 99.5 (Vickers HV 130 - 250). Machine Pack Count - Margin error of +/- 5%