Review on 🔒 100PCS-Black Cord Locks for Masks: OCEANTREE Elastic Adjuster Silicone Cord Stopper No Slip Earloop Toggles for Drawstring Buckle Clasp Spring by Dawn Fischer

That's what other reviewers said, and it's true. Quality control is not perfect. There was one (unusable) badly shaped cord lock in the bundle, but the rest was fine. In general they work fine. Since the elastic I bought in July started to shrink (after many washes) I decided to replace the old elastics with longer ones. Not only does this allow me to add extra length to compensate for the gradual shrinkage of the elastics, but it also allows each family member to adjust the elastics as needed. Too bad I didn't think of using them sooner. I use a buttonhole driver (a tool commonly used to thread elastics through cases) to thread the elastic through the buckles and it works fine; It won't be long before you get the elastic strap locks. I will probably buy more when they run out.