7/8 x 6 Reduced Shank Drill Bit (1/2 Shank)

They are actually stronger than most metal and chemical anchors

When a screw reaches the collar

9/16-12 x 6 Grade 8 Hex Cap Screw Yellow Zinc Plated

1/8 Cobalt Heavy Duty Jobber Drill Bit

21/64 Cobalt Heavy Duty Jobber Drill Bit (6) Gutter Screws 7/8 x 6 Reduced Shank21 64 Cobalt Heavy Duty Jobber Drill Bit . Heavy duty construction made to Type J aircraft specifications. Used for drilling holes in hard, tough materials such as stainless steel, titanium, high temperature and high strength alloys. High red hardness of cobalt permits speeds 30% greater than standard heavy duty split point (HSS) drills.