Material types are high carbon steel for hand tapping applications and high speed steel for machine tapping where critical dimensions are required. This machine screw "fractional plug" tap is ideal for routine maintenance, repair work and for rethreading where high accuracy and thread tolerance is not critical. The tap and recommended drill bit size are etched on each tool for easy identification. Fractional plug taps have 3 to 5 threads chamfered for easy starting and are the most common. Precision ground straight flutes provide rapid chip removal for efficient threading.