5/16-18X1 1/4 Serrated Hex Washer - Unslotted - 7/16" A.F.

SELF DRILLING SCREWS WITH MACHINE SCREW THREADS

Head Height: 1/4" Diam: .172
Head Height: 5/16" Diam: .208-.229
Case Hardened to Rockwell C50-56 (Core Hardness: Rockwell C32-40)
Steel Zinc Plated