This 6" Forstner Bit extension can be used with any Forstner Bit that has a 3/8" diameter shank. It is good to use when making peppermills and other projects with deep holes. The 6" extension is heavy duty with a 3/4" diameter. The end is turned down to fit in a 3/8" drill chuck.
Not Compatible with the Colt Maxi Cut Forstner Bits