These mask straps are designed to hold a 3ply mask securely to your head and take the pressure off of your ears. They are reusable and have a nice clasp to hold the ear loops in place. Many others I have tried are not secure.
This also are good for people with a smaller head or youth. It is important that the tension is enough to hold the 3ply mask against the skin. These straps have 9 possible positions for a custom fit.
Recommended procedure is to leave one side always connected. Place mask on face and reach around with both hands to secure the strap to the ear loop.
This could also be used for providing fit options on hand sew masks. They also can work on KN95 masks depending on head size and loop length.
2 packs (6 straps total) for $1.50.