SRAM RED XG-1190 Cassette - 11 Speed, 11-25t, Silver, A2

Top-of-the-line road cassette with the bulk of the cogs machined in one piece of tool-grade steel for low weight, no cog flex and high durability. Largest cog is aluminum.
Stealth Rings between the cogs minimize chain noise
Hollow steel dome makes for the stiffest gear cluster ever at the lightest weight
11 speed cassettes with 11 tooth cogs have the smallest cog located behind the cassette in the packaging