Designed for use with 18-8 stainless steel screws

Typical hardness is HRB 70-100

#1 Heavy Duty Jobber Drill Bit

1/4 x 1 1/2 Round Split Drive Anchor Zinc Plated (100)

Web construction is heavier than general purpose construction making it particularly suitable for cotter pin hole drilling and cross hole drilling in head of bolts

#28 Heavy Duty Jobber Drill Bit (12) 7/8-9 Grade 5 Hex Cap Screws Zinc Plated Designed for use with 18-8#28 Heavy Duty Jobber Drill Bit . Web construction is heavier than general purpose construction making it particularly suitable for cotter pin hole drilling and cross hole drilling in head of bolts. The heavy construction affords efficient drilling in stainless steel and other hard materials. The split point reduces the thrust requirements and minimizes walking.