If you need your glasses to fit securely whilst your active or playing sport, this 2 pack of retaining cords is the answer ! Quality thick cords with slidable rubber adjuster ensuring a tight fit.Just attach the cord to your specs, pop them on and tighten the sliding ajuster behind your head towards your scalp. Shorter design meaning less cord to hang down and get in the way.Black rubber loops. Suitable for most frames - specs, sun readers and sunglasses. Length 60 cm (between optical loops).