Limit number is h3; in accordance with us army drawing 11b5090651
An internal threading tool with longitudinally separated cutting edges designed to form specific threads.
Classification: Tools for tapping or threading, parts thereof, of base metal
NSN 6135-00-686-4777
NSN 5905-01-047-6914
NSN 5990-00-125-5036
NSN 6320-00-539-9283
NSN 5965-00-224-6034
NSN 6145-01-139-6557
NSN 6220-01-454-3580
NSN 5935-00-078-8593
NSN 5965-00-529-0602
NSN 6145-01-025-6514
NSN 5835-01-360-2657
NSN 6645-01-122-9430