TAP CARBON STEEL FRACTIONAL BOTTOMING 5/16-18NC-CARDED For cutting all types of internal threads. Standard pipe and metric available (sold separately). Made to exacting specifications. Tough carbon tool steel for long life. Cut cleaner more accurate threads and lasts longer. Right-hand thread taps in plug, taper and bottom styles. Drill size permanently marked on each tap High carbon steel fractional taper 5/16-18NC Made of super-tough carbon tool steel to exacting specifications, heat treated and tempered. Furnished in right hand threads with most sizes coming in special bright, hard chrome finish. Rust- resistant tarnish. 1-1/2 threads chamfered, use after threads have been started for tapping to bottom of hole. With size drill to use permanently on every tap. Fractional size. Carded.