Features: NPT - National Pipe Tapered; NPT is a US standard for tapered threads used to join pipes and fittings. ; ANSI/ASME standard B1.20.1 covers threads of 60 form with flat crests and roots. ; The taper on NPT threads allows them to form a seal when torqued as the flanks of the threads compress against each other. ; However a clearance remains between the crests and roots of the threads, resulting in a leakage around this spiral. ; This means that NPT fittings must be made leak free with the aid of thread seal tape or a thread sealant compound. ; For each 12" increase in distance from the end, the diameter increases by 3/4". ; BOTTOMING TAPS have a lead of two threads and are used to ensure minimum thread run-out when tapping to the bottom of a blind hole. Bottoming Taps are typically preceded by the use of a Taper or Intermediate Tap. ; Specifications:Diameter1/4"Pitch18 tpiLeadBottomingOverall Length62 mmTapping Drill11.1 mm