Micro 100 RR-1 Grooving Tool Sets; Material: Solid Carbide; Minimum Shank Diameter (Inch): 1/4; Maximum Shank Diameter (Inch): 5/16; Overall Length (Inch): 2-1/2; Minimum Hole Diameter - Smallest Bar: 0.25 in; Minimum Hole Diameter - Largest Bar: 0.3