... roller chainsSpecification:1. Simplex: 04B-1, 05B-1, 06B-1, 08B-1, 10B-1, 12B-1, 16B-1, 20B-1, 24B-1, 28B-1, 32B-1, 40B-1, 48B-1, 56B-1, 64B-1,72B-1.2. Duplex ... : 05B-2, 06B-2, 08B ... 8187 standards.Color: blue, black, yellow and natural industrial transmission chain (B series)