This is an original Chas H. Irwin expansive drill bit from the 1930’s. Called “The genuine and Original Irwin Bits”. The size is 7/8-3 inches or 22 – 76 mm. Made in Ohioa, USA. Comes in the original box and can still be used. This 21,5 cm or 8 1/2 inches long dril bit is a piece of machining history in it’s own right.
Check out the video from the Tool Man himself (1990’s series with Tim Taylor).