Thumb Screw Knurled With Shoulder Head Steel Thread Size 3/8-16 Length 1 In Head Diameter 1.375 In Head Height 0.313 In Shoulder Dia 0.750 In Screw Shoulder Length 0.688 In Class 2A Rockwell Hardness B68-B71 Tensile Strength 57 000 PSI Finish Black Oxide