PG 970 Cassette

Information from: http://www.sram.com/sram/road/products/pg-970-cassette.

If you're a rider whose performance needs or riding style dictates that you run an 8 or 9 speed drivetrain, the PowerGlide II 970 is your only choice for light weight, strength, and precise shifting.

Specifications

Available in: 12-26, 12-23, 11-23, 11-21

Recommended Chain: PC 991 HP, PC 991 XS, PC 991, PC 971, PC 951