Flat Omega Chains #1029 (1.6 mm – 4.5 Gr./Ft.) #510 (2.5 mm – 11.2 Gr./Ft.) #1020 (3.0 mm – 11.9 Gr./Ft.) #1954 (3.7 mm – 14.3 Gr./Ft.) #1901 (6.4 mm – 23.0 Gr./Ft.)