Whether you're trying to mount your rotor with an IS or post-mount setup, we've got the right Shimano Disc Brake Adapters for the job. All you need is the skeleton key to understanding Shimano's admittedly byzantine model naming convention. SM-MA stands for Shimano Mount Adapter, so that'll be universal across models and can be safely ignored now that you're here. The rest of the model name is the important part. An "F" denotes the front brake and an "R" denotes the rear brake. The following number (160, 180, or 203) is, of course, the rotor size, with special parentheticals for 203mm rotor conversion. The final two initials respectively describe the caliper type and the frame/fork mount type, corresponding to either ISO or post-mount.