The soft and adjustable neoprene strap provides a comfortable fit and secure hold for all day wear. Made with quality neoprene, which are elastic, durable, lightweight and washable. The product itself can float on the water(but it is not guaranteed to float with glasses). You can insert your eyeglass frame into both end of strap, and slide it up and down to achieve optimal fixing effect, keep the glasses in place and you can wear them on the head or around the neck to avoid missing your eyeglasses. The neoprene eyewear holder allows you to enjoy yourselves when rock climbing, cycling, hiking, travelling, fishing, surfing, boating, etc. Adult size we have 2 kind 16.5″ and 13.2″. We also for kid size length 9″. Contact us please.