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 minimum steel teeth and alloy Spider construction for rigidity, lightweight and durability dyna-sys and dyna-sys11 10/11-speed chain compatible available in 38T/34t chain ring fixing lock nut Not included for 50 mm Chain line.