The Shimano XT CS-M770 9 Speed Cassette has been redesigned by Shimano to give riders confidence on all their mountain rides. The XT CS-M770 features Shimano's Hyperglide sprockets to give this cassette specifically positioned ramps and tooth profiles to give you faster and more responsive shifting. The aluminum carrier supports the steel cogs to give them increased rigidity while reducing overall weight. To help prevent problems because of an overshift, the XT CS-M770 has pins on the backside of the tallest sprocket that keeps the chain on the sprocket. The sprocket sizes are 11-13-15-17-20-23-26-30-34. This cassette features an 11-34 ratio.