Bolts are designated by grade or property class which indicates inch or metric respectively, type symbolising raw material chemical composition and by style symbolising Heavy Hex bolts or Twist Off style.
ASTM Nut & Washer Specifications
ASTM A563 Heavy Hex
Nut Imperial or Metric
ASTM F436 Hardened Washer Imperial or Metric
ASTM F959 DTI Washer Imperial or Metric
Group of Companies