3/8" Major Diameter X .625" Reach, Sharp Corner, 2° Angle Reverse Taper Carbide Back-Draft Cutter 0.500"Loc, 3/8"Shank, 2-1/2"Oal .320" Neck Diameter, 2° Angle Per Side Back Taper, 15° Helical Flute. Back Draft Cutters Allow Machining Right Next To A Pocket Wall Without Damaging The Wall. Internal Tool Part #45-1130 Internal Tool