ZELX SS 1/4-18 NPT Spiral Fluted Black Oxide Tap Manufacture: YMW Mfg Part Number: 383643 Size: (NPT) Number of Flutes: 4 Flute Style: Slow Spiral Thread Lead: 2-1/2 to 3-1/2 Finish/Coating: Black Oxide Tap Material: Vanadium High Speed Steel Oversize: (Yes/No) No Length of Thread 1-1/16 Overall Length: (Inch) 2-7/16 Thread Standard: NPT Pipe Tapping Materials: Steels and Ductile Iron Tapping Steels: 15-18 SFM, Tapping Ductile Iron: 10-15 SFM