We all knew it was coming, but the XG-1090 cassette is better than we could have imagined. Super light, super durable, and extremely quiet, the Sram Red XG-1090 Powerdome X cassette is the most advanced cassette ever made. The eight middle cogs are machined from a single piece of heat-treated, high grade tool steel. Tool steel is known to be extremely durable since it's primarily used for making premium tools (hence the name). This equates to a cassette that will last much longer than any other cassette on the market.
It doesn't stop there however. The largest ring is made from Aluminum which brings the weight down even more. Machining holes through the body made the Powerdome X much quieter than its predecessor, but Sram wasn't content. Sram installed StealthRing elastomers between the cogs and refined the tooth profiles to eliminate vibration and noise associated with the chain engaging the cassette. Power transfer is unaffected however and the result is an incredibly quiet ride experience, especially when used in conjunction with the 2012 Red Rear Derailleur. Because 2012 Red is 10 speed compatible, the XG-1090 Powerdome X cassette can be used with any Sram 10 speed road or mountain group.