Large = Average Sized Grown-Up (that's subjective, I know but you know if you're little or large or somewhere in-between)
Extra Large = For Our Bigger and/or Beardy Neighbours
These East Van Mom-made masks are now three layers thick, with the middle layer being polypropylene, as the smart folks up top have recommended. They're super comfortable, cute & sassy and come in untampered-with packaging, for that extra safety factor.