NPT and BSP Available – Perfect for Cuts Internal Threads in Pipes. Durable and Harder Than Carbon Steel – Our GCR15 Material Makes All the Difference. Includes size of: 1/8″ – 27 npt, 1/4″ – 18 npt, 3/8″ – 18 npt, 1/2″ – 14 npt, 3/4″ – 14 npt.