USAmade 104BCD 30T Narrow Wide Alloy Black Mountain Chainring CONTROL 2016 Collection- NEW Unique alternating Thick-Thin tooth profile for excellent chain retention Fully CNC machined with 6061-T6 aircraft aluminum alloy for lightweight strength Certified to ISO 9001:2008 standard High performance chainrings at great prices Compatible with 8, 9, 10 and 11 speed or single-speed drivetrains