There’s no need to explain the many benefits of sunglasses - they protect your eyes, make you look cool or make you look incredibly cool.
Similarly, there is no need to explain the benefits of a strap for your shades - it prevents you from losing them, so your eyes stay protected and you keep looking cool (incredibly cool)...

Our thin Specs Straps are made of soft leather in fashionable colours. They are the ultimate add-on to your glasses not just in summer, but all year round. Naturally, the Specs Strap can be used with sun or prescription glasses!

Also, the integrated clasp allows you to fasten the strap around your head for a tight hold when you do sport or the like.