SafetyGlo Collars, Leashes and Leads utilze LED (light Emitting Diode) technology to produce a bright, glowing light that is visible from over 500 yards away. Unlike traditional reflective collars & leads, noexterior light source is needed to create visibility. No batteries needed, these items come with a detachable, relaceble power pack that can be recharged using solar rays or USB connectivity. Materials: Nylon. Dimensions: 2*1.5*19