Classes of Internal Threads and Classes of Cutting Taps • For Unified Fine Threads Description of products Sizes Basic Pitch Dia. (+)μm 3B 2BX 2-64 UNF 2B GH2 Tap class (3B・2B) 3B 2BX Oversize Tap class (2BX) 3-56 UNF 2B Yamawa GH class for Internal threads 2B GH2 Yamawa Oversize GH class for Internal threads 2B 3B 2BX 2B Internal threads 3B 4-48 UNF GH2 Internal threads 2B 3B 2BX 5-44 UNF 2B GH2 3B 2BX 6-40 UNF 2B GH2 GH7 3B 2BX 8-36 UNF 2B GH3 GH7 3B 2BX 10-32 UNF 2B GH3 GH2 GH4 GH5 GH6 GH7 3B 2BX 12-28 UNF 2B GH3 3B 2BX 1/4-28 UNF 2B GH3 GH4 GH5 GH6 GH7 3B 2BX 5/16-24 UNF 2B GH3 GH4 GH5 GH7 3B 2BX 3/8-24 UNF 2B GH3 GH4 GH5 GH7 3B 2BX 7/16-20 UNF 2B GH3 GH5 GH6 GH7 3B 2BX 1/2-20 UNF 2B GH3 GH5 GH6 GH7 3B 2BX 9/16-18 UNF 2B GH3 GH5 GH7 3B 2BX 5/8-18 UNF 2B GH3 GH5 3B 2BX 3/4-16 UNF 2B GH3 GH5 GH7 3B 2BX 7/8-14 UNF 2B GH4 Information Technical GH6 3B 2BX 1-12 UNF 2B GH4 Technical-16 787