5/16-18X3/4 Serrated Hex Washer - Slotted - 7/16" A.F. - Self Drilling Screws - Zinc

Head Height: 1/4"; Diameter: 0.172 - 0.190"
Head Height 5/16"; Diameter: 0.208 - 0.229"
Across The Flats = 7/16"
Case Hardened to Rockwell C50 - 56
Core Hardness: Rockwell C32 - 40
Steel Zinc Plated