Works ONLY with Shimano 12 speed CNM9100, 8100 & 7100 chains \n Oval rings help the rider to spin smoother and more efficiently \n Example: 32t is equivalent to 30t at dead spot and 34t at the power zone \n Replaces the existing chainring and spider on 3bolt SRAM cranks. Also fits Cane Creek eeWings \n Narrowwide tooth profile keeps the chain snug, allowing you to leave the chain guide behind \n Designed in UK, manufactured in Poland