**Snell Approved Racing Helmet's - SA2010 vs M2010**

So does anyone know the deal with the difference in how fast you can go with each helmet?

I am trying to compare Full Face Helmets. I know that M is for Motorcycle and SA is for Auto's

Lots of guys run with the M and from what I am reading it is good for anything 13.99 & Under if it is Full Face?

What helmets are you guys using?