the hardness rating is HRC 24-35

you protect your surfaces from enduring sudden failures or breakages while promoting long-term durability

Open-end button head rivets offer the broadest selection of sizes available

Screws with a diameter over 1 ½ inches have a hardness rating of HRB 95 - HRC 35

1 1/4-12 Slotted Hex Nut Zinc Plated

1/16 Cobalt Heavy Duty Jobber Drill Bit (12) Flat Washers Silicon Bronze the hardness rating is HRC1 16 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.