Elastic Cord Locks Disc Face Mask Earloop Adjusters made of non slip silicone. Elastic cord adjustment buckle is soft lightweight sturdy and not easy to break, will last for a long. For your mask wearing comfort, use these adjusters to tighten or loosen your elastic ear loops. Stoppers have two different size holes on the ends which help secure elastic or ribbon in place (4mm and 2mm). You can use these with 1/8" and 1/4" braided elastic, 1/8" rolled elastic cord, and 1/4" ribbon with no problems. These cord adjusters are great to make masks fit just right behind the ears and are very comfortable. They are difficult to place with just your fingers. You really need a loop turner, needle or small crochet hook for easy threading.