absoluteBLACK Oval 104 BCD Chainrings for Hyperglide+ are designed for any cranks that use a 104 BCD mounting interface. These chainrings will only work with Shimano CN-M9100 8100 & 7100 Hyperglide+ chains due to different thickness and shape of the teeth. They are crafted from CNC machined 7075 aluminum and feature an anodized finish for exceptional durability. Ovality has been optimized for each chainring size ranging from 10.2 – 14.4% with timing of 110.5 – 116.3 after TDC (top dead center).