Machine Screw Tap, National Course Thread, #4 x 40

#4 x 40, national course thread, machine screw 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 drill bit #43 or 5/64".