New Old Stock IRWIN Unibit #1 USA made HSS Step Drill Bit, 1/8-Inch to 1/2-Inch , 1/4-Inch Shank (10231) Drill chuck arbors and longevity

and longevity

This is a very rare super high quality tool

these blades are capable of cutting even the most difficult metals with great accuracy and combine consistent high performance with long life

Seemes to be various brands

Tap and drill gage has a convenient chart stamped on the face showing the correct tap and body drill size

New Old Stock IRWIN Unibit #1 USA made HSS Step Drill Bit, 1/8-Inch to 1/2-Inch , 1/4-Inch Shank (10231) Drill chuck arbors and longevityNew Old Stock IRWIN UNIBIT USA made Step Drill Bit, 1 8 Inch to 1 2 Inch , 1 4 Inch Shank (10231) Product description Single flute cutting edge for greater control through steps, Hex shank prevents slipping in drill chuck, SpeedPoint tip penetrates fast and prevents walking, Ideal for drilling holes into thin materials like stainless steel, copper, brass, aluminum, plastic, Self Starting 1 8" Maximum Material Thickness Date on the packaging has