Use a Two-Flute bit where fine finish is paramount. Two flutes balance the bit, eliminating vibration that degrades the cut finish. Two cuts per revolution yield a smooth surface, but feed rate is slightly reduced, #45220, diameter (D): 3/8, cutting Height (B): 1-1/4, Shank (D): 1/4, overall length (L): 2-1/2, flutes: 2, 45220 carbide Tipped straight plunge high production 3/8 dia x 1-1/4 x 1/4 inch Shank