Irwin HAN8149 High Carbon Steel Machine Screw, 9/16 x 18

National fine thread. Fractional tap. Carbon steel. Ideal for routine maintenance. Repair work & for rethreading where high accuracy & tolerance thread is not critical. Straight flutes are ground to provide rapid chip removal for efficient threading. Designed for hand threading work in a variety of materials taps produce a class 2B thread. Use 33/64″ drill bit.