ISO 4468:2009 Gear hobs-GB/T 6084-2016 General technical specification 

gear hob module: m0.5-m1, m1-m2, m2-m3.5, m3.5-m6, m6-m10, m10-m16, m16-m25, m25-m40

accuracy requirement of hobs: AAAA, AAA, AA, A, B

bore: 8mm, 10mm, 13mm, 22mm, 27mm, 32mm, 40mm, 50mm, 60mm, 80mm

number of starts: single, two, three, four, five, multi-starts

material: HSS M2, M35, M42, ASP2052, S390, and Carbide