LWCUSNJ 1/4" - 18 NPT Pipe Tap,1pc M2 NPT Tapered Pipe Thread Tap, Used for Conventional Machine Tapping or CNC Tapping, Can Tap Steel and Stainless Steel: Amazon.com: Industrial & Scientific
Amazon.com: 6-Piece NPT Pipe Tap Set, 1", 3/4", 1/2", 3/8", 1/4", 1/8" NPT Tap Set, Carbon Steel Hand Threading Plumbing Tap Set for Accurate Threads, Assorted Plumbers Mechanics DIY Thread cutting tools :
Amazon.com: 3/8"-18 NPT Tapered Pipe Thread Tap High Speed Steel Pipe thread tap : Industrial & Scientific
Taper Pipe NPT Taps HSS - 1/16 - 1/2 Inch Size ID 20970-