Oval Herringbone Chains OHB-35 (1.6 mm – 2.3 Gr./Ft.) OHB-40 (1.8 mm – 3.0 Gr./Ft.) OHB-50 (2.2 mm – 4.4 Gr./Ft.) OHB-60 (2.6 mm – 7.0 Gr./Ft.) OHB-70 (3.1 mm – 8.9 Gr./Ft.)