Micro 100 QT-187-C4 Boring & Grooving Bar Holders; Inside Diameter (Inch): 3/16 ; Inside Diameter (Decimal Inch): 0.1875 ; Outside Diameter (Decimal Inch - 4 Decimals): 1.5748 ; Overall Length (Decimal Inch): 2.8666 ; Head Diameter (Decimal Inch): 0.