OSG Tap and Die, Inc. 1"-11-1/2 5RX NPTF Pipe Tap, OSG 1253000, Thread Size (Inch): 1 - 11-1/2; Thread Standard: NPTF; Material: High Speed Steel, Finish/Coating: Bright; Projection (Decimal Inch): 0.5781, Helix Angle: 15, Taper Pipe Tap, Short Projection Pipe Tap for Ferrous and Non-ferrous Materials, Aluminum Alloys, Cast Aluminum, Cast Iron, Carbon Steels