Fine-finish holes in hard metals. This 9-piece set with 1/2” shanks, fits head 47-705. This set comes with 3 boring bars that bore holes with a minimum diameter of 3/8" and overall lenths of 2-1/4", 2-1/2" and 3". 3 Boring bars that bore holes with a minimum diameter of 1/2" with overall lengths of 2-1/2", 3" and 3-1/2". 3 boring bars that bore holes with a minimum diameter of 5/8" and overall lengths of 2-1/2", 3-1/2" and 4".