These stereo earmuffs have individual volume control on each ear. Slimline and folding they fit neatly into a pocket or case so as to be on hand when needed. Solar powered, there is never any need to woory about whether the batteries are charged or likely to run out! They need light, as opposed to sunlight, to charge and are able therefore to be used in all conditions and also charge in artificial light. 25 attenuation.