Shimano Ultegra 6800 11 Speed Cassette
The new Ultegra 6800 11-speed cassette has a wider range of rider-tuned gearing options. It's steel cogs are treated with a special coating that helps resist wear and facilitates precise shifting. To lighten things up Shimano gave the 6800 cassette an alloy carrier and made the 2 largest cogs on each cassette out of titanium.
Please Note: The 6800 cassette is not compatible with HG 8-10sp freehubs.