"SRAM RED E1 Cassette (Model ID CS-XG-1290-E1) 12 speeds offered in a 10-28T, 10-30T, 10-33T or 10-36T range. Pair with any of our chainrings for your dream gearing setup. 
 
Designed for smooth and fast shifting
10-30T and 10-36T options available in RED for the first time
Designed to work with an XDR™ driver body
One-piece machined steel X-DOME design for weight savings
Available in 10-28T, 10-30T, 10-33T and 10-36T"
 
- SRAM