You are right to ask the question. Here’s why.
UCR’s DE program requires a helmet certified by the Snell Foundation and we will inspect the helmet to find the Snell sticker (on the inside). For DE, we require Snell M or SA = Motorcycle or Special Applications. SA helmets are (only) mandated for racers, not DE.
Here’s YOUR problem. The new Snell certification stickers come out only once every FIVE years. I would guess that no helmet currently on the shelf at any local shop has a sticker newer that 2010 because they haven’t received any helmets with the 2015 sticker. That means that your helmet is INSTANTLY five years old when you walk out of the store. We allow 10 (sticker) years and so all the 2005 helmets will need to be replaced this year. That can’t happen until inventory becomes available.
Here is the Snell testing standard:
Here is the link to Snell M2015 approved helmets.
I would expect to pay about $200 for a Snell M2015 helmet. I would not pay more than half for a Snell M2010 helmet.
Your best bet is to phone local shops to ask if they have or can get a helmet in your size with a Snell M2015 sticker. Wait until they can. You can go to any shop and check to find the size that suits you best and then wait for the 2015 sticker.
If you need a large size, Stephen Goodbody has a loaner.