Two Sizes for Different Needs: 5pcs adjustable cassette buckle Skin Friendly and stretchable: The 0.4inch wide elastic band are made of Lycra, same material with bra strap, can stretch from 5inch to 9inch for most head sizes. Perfect for health care workers, doctors, nurses, med students and someone who needs to wear mask for extended time without catch in hair. Reliving You From Slipping and Protecting the Ears: Save our ears from suffering the pressure of wearing face mask for the whole day. Perfect solution when mask fall off when it is not fit our face. Versatile Accessory: For use with most face covering including cloth, disposable, homemade or DIY masks and more, adjustable for comfort and custom fit. And it could also used as aa secure buckle to keep the bra in place, hide bra strap when wearing a sleeveless top,and replace stocking garter clips. Reusable, Hand-washable, Multi-use: Use with your face covering every day, hand washable construction, use your extender multiple times.