ACID CHAINRING HYBRID PRO HPA BLACK 42TThe innovative Narrow Wide technology not only prevents the chain from slipping off this ACID chainring but is also quieter. The smart thick thin profiling of the teeth holds the chain relentlessly, even in rough terrain. The direct mount construction effectively transfers the pedal force from the crank to the chain and saves weight. With their current design, our ACID chainrings are also an optical highlight on any bike.