1.PMMA(optical acrylic) materials 2.limpid ... 0.3mm Focal length/Magnification: 520mmfeature ad advantages:1.high light transmittance2.limpid transparent3.high light penetrability, ... for PROJECTOR,PROJECTOR,EPIDIASCOPE and ,also suitable for Solar energy collector system, start a fire under sunlight, ... hot water heater, solar furnace, stage light,LCD projector,AV projector,HOME ...