Mike, Measured the bit, Shank is 1 1/8 So 15/16 should be amount put into the arbor, this only leaves 3/4 of an in left sticking out. All of the bits I got in this starter kit are short, they work fine without the guide bushings, except some are too short to go all the way thru the bushing to contact what I want to cut. I have noticed that the P.C. bits have a longer shank. John |