Each of my masks come with a little hidden metal wire inside the top so that you can mold it snug around the bridge of your nose and has a little opening on the inside where you can insert filters. I've recently added plastic toggles and a lengthened elastic, so that you can now adjust the mask to your desired length. Comfort is key!
Sizes come in Kids, Adult S/M, Adult L, and Adult XL.
*** Please note that kids masks do not come with a metal wire in the nose.