It’s K or SA2015 rating at the moment. K is for karting rated helmets, so without Nomex. SA is the standard for Nomex or fireproof auto helmets. M2015 might also be allowable at some clubs.
CMR refers to child-specific helmets, so unless you have a tiny head, that probably wouldn’t be a good call. These are smaller shells and usually extra small sizing.
Snell 2020 rated helmets will be coming the end of the year so if you can wait a little, there might be some smoking deals coming on 2015 rated helmets. Helmet ratings are usually good for 10 years, so the 15s are still good until 2025.