Croakies Terra Spec Cord Adjustable Eyewear Retainer - Royal Thanks to the universal compatibility of our Spec ends Terra Spec Cords fit the widest range of eyewear styles. Made with high quality braided nylon climbing rope and featuring an adjustable slider bead for a secure fit when chasing your next adventure. Thanks to the universal compatibility of our Spec ends Terra Spec Cords fit the widest range of eyewear styles. Made with high quality braided nylon climbing rope and featuring an adjustable slider bead for a secure fit when chasing your next adventure.