I ordered a few of these for my Aeon helmet.
I change them out at least once a season, and I always remove, rinse, and dry these pads after a hot or sweatly ride.
Nobody likes a stinky helmet with worn-out pads, so frequently replacing these pads (only $5 a set) will keep your expensive Aeon good as new season after season.
Also, rinsing your helmet under cool running water in the kitchen sink will get rid of any salt and sweat. I never use anything harsh, just a quick rinse does the trick.
For some reason, these aren't hard to find. My helmet was smelling like I was riding 2x a day. Rather than buy a new Giro, I thought I'd replace the pads. After striking out at Giro.com and a few other places, I found them at biketiresdirect.com. They arrived quickly and fit exactly right.