Master Mechanic, 5/16" x 4-1/2", High Speed Steel With Cobalt Drill Bit, 135 Split Point, Jobber Length, Straight Shank, 135 Split Point Design With 4 Cutting Edges Allows Quick Penetration & Eliminates Walking, 8 Percent Cobalt Content Provides Heat Resistance & Delivers Maximum Cutting Efficiency At Temperatures In Excess Of 1,000 Degrees Fahrenheit, Recommended For Drilling In Hard Metals Such As Heat Treated Steel, Stainless Steel, Chrome, Manganese Steel Plus Titanium & Armor Plate, Carded.