Dynamic Chain Engagement (DCE) is used to hold the chain and help prevent chain jump out. This is achieved by using a broader and taller tooth profile in conjunction with a special hooked leading edge and alternate profiled tooth shaping. This provides superior chain retention, lower driving sound, increased durability and drag to a minimumSteel teeth and alloy spider construction for rigidity, lightweight and durability.Key Features:Dyna-Sys and Dyna-Sys11 10/11-speed chain compatible,Available in 38T/34T,Chain ring fixing lock nut not included for 53 mm boost chain line.