Micro 100 QD1-MR16-5-1000 Boring & Grooving Bar Holders; Inside Diameter (Inch): 5/16 ; Inside Diameter (Decimal Inch): 0.3125 ; Outside Diameter (Decimal Inch - 4 Decimals): 1.0000 ; Outside Diameter (Inch): 1 ; Overall Length (Decimal Inch): 3.2000