... higher than the manufacturing precision, and therefore easy to become series mass production, production costs are lower, using highly popular. ... , 6904, 6905, 6906, 6907. 6908, 6909, 6910; 6000 Series: 605, 606, 607, 608, 609, 6000, 6001, 6002, 6003, 6004, 6005, 6006, 6007. 6008 ... , 6009, 6010; 6200 Series: 625, 626, 627, 628, ...