Extension Tap, Thread Size 3/8 In.-16, UNC, Overall Length 6 in, High Speed Steel, Black Oxide, Right Hand, 16 The black-oxide finish on these taps retains lubricants to improve the taps' wear resistance and chip flow. Black-oxide taps should only be used on ferrous metals. High-speed steel taps provide good wear resistance in general purpose tapping applications in a range of materials.
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