This is a 46-tooth outer chainring for 50.4bcd cranksets. It's made from 7075 alloy for extra long life and lightweight performance. It features modern shifting aids like ramps and pins and is compatible with 5-10 speed drivetrains on non-VO spiders. If you are using this are a replacement of a current generation VO 50.4 crankset, then everything will be 5-11sp compatible.