Micro 100 QT-375-C3 Boring & Grooving Bar Holders; Inside Diameter (Inch): 3/8 ; Inside Diameter (Decimal Inch): 0.3750 ; Outside Diameter (Decimal Inch - 4 Decimals): 1.2598 ; Overall Length (Decimal Inch): 2.6161 ; Head Diameter (Decimal Inch): 0.8