BOX One Prime 9 Chain DLC - BlackPrime 9 Technology for wide range without complexity Wider chain is strong and durable 9 speed chain has outer width of normal 9 speed but a narrower inner width to match 10 11 speed narrow wide chainrings. Compatible with most 10, 11, and 12 speed chainrings as well as BMX 3 32 inch chainrings and cogs 8 speed chain has outer width of normal 8 speed but a narrower inner width, optimized for use with Box Four Narrow Wide chainrings 3rd party web sales