The anti-slip silicone strap is more suitable for acetate glasses legs, not for thin metal glasses legs, it is applicable to the eyeglasses legs' tail width up to 9mm. When you're doing sports or engaging in outdoor activities, your glasses or sunglasses may fall with a slight knock. At this time, you need one glasses anti-slip strap for use. The glasses anti-slip strap is made of durable soft elastic silicone material and suitable for adults and children to wear. You can easily mount the anti-slip strap on your glasses legs and wear it on your head, to well prevent your glasses from falling. Features color: 5 colors. Material: durable soft elastic silicone. Total length: 22cm. (elastic design allows you to stretch the strap up to 60cm). Hole size for glasses legs: 0.9cm x 0.2cm. 100% brand new and high quality eyeglasses sunglasses glasses anti-slip elastic silicone headband strap. Elastic silicone strap design, make it suitable for both adult and children to wear. Installing the anti-slip strap on your glasses legs and wearing it on your head, can effectively prevent your glasses from falling when you are doing sports. Package including: 5 x NUOLUX eyeglasses sunglasses glasses anti-slip elastic silicone headband strap.