Fitz-Rite test bars are made in the USA and are held to the highest standards for checking the accuracy of your CNC machining centers' spindle. They are manufactured from mill-certified hardened alloy steel. The shank is held concentric to the taper within one tenth (TIR .0001"). The fast taper is made in accordance with AISI / ASME B5.50 standards and precision ground to met AT-3 tolerance for maximize spindle contact.
Test bars require a retention knob fitted to your machine specifications. Retention knobs are available for purchase separately.