Precision Twist Drill Jobber Length Drill Bit, General Purpose Heavy Duty, Series: R15B, Imperial, O Drill - Letter, 0.316 in Drill - Decimal Inch, 4-1/2 in Overall Length, 4XD Cutting Depth, 2 Flutes, Spiral Flute, 3-3/16 in Flute Length, 0.3161 in Shank, Straight Shank, 135 deg Point, Split/Self-Centering Point, Right Hand Cutting Direction, HSS Cutting Edge, No Through Coolant, HSS, Steam Tempered, Dark Gray, Applicable Materials: Magnetic Soft Steel, Structural Steel/Case Carburizing Steel, Plain Carbon Steel, Alloy Steel/Hardened and Tempered Steel, Free Machining Stainless Steel, Austenitic, Ferritic + Austenitic, Martensitic and Graphite/Malleable Cast Iron