A paper-like multilayer barrier film comprises a filled polypropylene layer and several unfilled layers. The device is comprised of metal housing components attached with metal loops and cable loops to provide a pivotal axis point which may be gripped and pulled to provide resistance leveraging the pivotal axis point of the device, or which may be gripped along the metal housing components to vary the exercise regimen and to provide resistance to different muscle groups. The laser amplifier includes at least one focusing optical element disposed in the laser radiation field between two adjacent laser-active media.