Giantree 12 Pack Spring Cord Lock, Double Hole Drawstring Stopper Fastener, Black Plastic Spring Cord Locks, for Drawstring Sweatpants Hat Hoodie String Clip Elastic Shoelace Lock Swim Goggles (12)

Cool mask! Are those leather strings for holding it on? May I recommend a cord lock to help you fasten it onto your head. (EDIT: as opposed to trying to tie a knot which can be a PITA) Pass the strings through those, then pull tight until the mask is comfortable. I have used these in the past, and they hold up quite well. I hope this helps! (https://a.co/d/5axXoTi)