This one’s only for the serious weight weenies. At 134 grams (11-28-tooth), the Uno cassette may be the lightest cassette on the market. It was designed to be used with Rotor’s Uno group, but it’s also compatible with Shimano and SRAM drivetrains.
A 7075 heat-treated aluminum structure keeps weight to a minimum without diminishing strength, and the two-piece construction (all but the two largest cogs are one piece) only adds to the durability.