Grade Markings for Steel Fasteners
From Free Knowledge Base- The DUCK Project: information for everyone
Bolt Grade Markings and Tensile Strength - SAE and ASTM.
- Bolts,Screws,Studs with 3 symmetrical tick marks on the head = Grade 5
- Bolts,Screws,Studs with 5 symmetrical tick marks on the head = Grade 7