Classes of Internal Threads and Classes of Cutting Taps Description of products • For Unified Coarse Threads Sizes Basic Pitch Dia. (+)μm 3B 2BX 2-56 UNC 2B GH2 Tap class (3B・2B) 3B 2BX Oversize Tap class (2BX) 3-48 UNC 2B Yamawa GH class for Internal threads 2B GH2 Yamawa Oversize GH class for Internal threads 2B 3B 2BX 2B Internal threads 3B 4-40 UNC GH2 Internal threads 2B GH3 GH4 GH5 3B 2BX 5-40 UNC 2B GH2 3B 2BX 6-32 UNC 2B GH3 GH2 GH4 GH5 GH6 GH7 3B 2BX 8-32 UNC 2B GH3 GH2 GH4 GH5 GH6 GH7 3B 2BX 10-24 UNC 2B GH3 GH5 GH6 GH7 3B 2BX 12-24 UNC 2B GH3 3B 2BX 1/4-20 UNC 2B GH3 GH5 GH6 GH7 3B 2BX 5/16-18 UNC 2B GH3 GH5 GH7 3B 2BX 3/8-16 UNC 2B GH3 GH5 GH7 3B 2BX 7/16-14 UNC 2B GH3 GH5 3B 2BX 1/2-13 UNC 2B GH3 GH5 GH7 3B 2BX 9/16-12 UNC 2B GH3 3B 2BX 5/8-11 UNC 2B GH3 GH5 3B 2BX 3/4-10 UNC 2B GH3 GH5 3B 2BX 7/8-9 UNC 2B Technical Information GH4 3B 2BX 1-8 UNC 2B GH4 Technical-15 786