CNC machined anodized alloy adaptor, this adapter fit post mount only, mount bolt center to center 74mm, please measure and make sure your bike is post mount type base, use for install 200mm 203mm rotor caliper on 180mm PM post, also for install 180mm rotor caliper on 160mm PM post, compatible 74mm fork/frame post mount, compatible with Shimano, Sram, Avid and other caliper.Package include: 1x post mount adapter, 2x mount bolts with spacers whashers.