The lightest and most refined solution for Cannondale Hollowgram cranks, period. Hollowgram spiderless chainrings allow for flawless 1x9/10/11 drivetrain setup. 5.7mm offset provides better chainline than other brands. Compatible with Cannondale Hollowgram Si, SiSL, SiSL2 and newest F-Si. Narrow/Wide tooth profile helps prevent dropped chains. Oval construction maximizes pedal stroke and torque transfer. 7075 Aluminum construction