Material: Soft Flexible Silicone Plastic. Color: Black and White for your choice. Package: Including ( 250 PCS Cord Locks 500 PCS Cord Locks). Size: About 0.39in x 0.23in (Length x Diameter). HOW TO USE IT : Step 1:Put the Elastic adjuster through the crochet hook Step 2:Put the mask string on the crochet hook Step 3:Grab the elastic and pull through Step 4:Adjust the elastic band of the mask according to your face and comfort level.Customer Service: Customer satisfaction is very important to us, if you have any questions, please contact us at any time, we will reply you within 24 hours and provide you a good service. One size fits all: Suitable for All Different Sizes of mask Straps Bands /8 Straps,1/5 Straps,1/4 Straps,5/8 Straps Wide Application: Multi functional cord locks for drawstrings, round and flat elastic bands, sewing, lanyard, sport wear, clothing, decorating, crafting, beading, jewelry making, florist arranging, handmade DIY, gardening, or wrapping and more. Adjustable cord stopper: is easy to adjust the length of the cord to suit for kids. It is more comfortable to apply. Easily slide over the pearl cord with a soft adjustable buckle that holds the face cover securely to the wearer. Premium Soft Material: Our cord locks are made of high-quality soft silicone. They are safe, healthy, lightweight, durable, no odor and not easily break, you can reuse these cord stoppers for a long time. Buckle closure.