The anti-slip silicone ends is more suitable for Acetate Glasses Legs, NOT for Thin Metal Glasses Legs. 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 elastic band with soft silicone ends, 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. It is applicable to the eyeglasses legs' tail width up to 10mm.