Fresnel lens(solar energy),Silion on glass, strong and shock protected Fresnel lens(solar energy)Material: silicon with glassSilion on glass, strong and shock protectedSize: 520x420mm, total 80 unit, each unit: 50x50mmFocal length: 70mmDurability: 30 yearsThickness: 3.2mmOptical effiency: 81%we can send further information after inquiry. Fresnel lens(Lens concentrates)