microSHIFT Advent MX G-Series Cassette - 11-Speed, 11-50t, Aluminum Spider, Silver/Black, For XD DriverThe Advent MX G Series cassette is the smoothest shifting, most durable cassette that they've ever made. That all starts with SpeedRamp, a series of discrete shifting ramps that move the chain quickly, quietly, and precisely under load. The cogs themselves have been upgraded as well: the profile has widened to 1. 8mm, and the first seven cogs (11 28) have been constructed using full chromoly steel, helping to outlast even the most robust competitors.