The M771 XT cassette is one of the best ways to lose a chunk of weight without breaking the bank. Designed to work with Shimano's new Dyna-Sys 10-speed system, it features an aluminum carrier that saves weight and adds rigidity, meaning you get better shifts, more efficient power transfer, and increased happiness. The steel rings used on this cassette will give you a longer wearing piece that will provide more miles of fun. The cut way design sheds mud for when the skies open up and you get caught out on the trail.
The new Shimano 10 speed mtb drivetrain is amazing... and the same goes for this XT cassette. A much cheaper option compared to XTR cassette but still shifts just a crisp. The trade off is a few extra grams to save some green. I am running this XT cassette with XTR shifters/rear derailleur and XT chain... works wonderfully!