E*Thirteen Helix Race Cassette Precision Shifting Performance Shifting is an important part of riding a bike. However, you don't want just any cassette on the back of your bike, causing missed or slow shifts. The E*Thirteen Helix Race Cassette is engineered to deliver precision shifting performance with an industry-leading 578% gear range. The proprietary 9-tooth smallest cog combined with the 52T largest cog enables a smaller chainring for improved clearance, lighter system weight, and a lower bail out gear ratio without high gear compromise. Features Seamless cross-compatibility with Shimano, SRAM, and TRP 12-speed drivetrains2-part design provides strength, stiffness, light weight, and ease of service Aluminum and steel clusters can be replaced separately to reduce cost9-tooth high gear allows use of smaller chainrings for clearance and weight savings Designed to fit XD and XDR drivers only Perfect for electric bikes and acoustic bikes Specifications Cassette Body Type SRAM XD/XDRCassette Cogs9-11-13-15-17-20-23-27-31-36-43-52Drivetrain Speeds12Cassette Material Aluminum/Steel Weight392g | E. thirteen | Helix Race Cassette 9-45T | Grey