ptical B270 glass dia.7.8mm*1.2mm windows protect camera lens and improve photographic lens. VY Optics Photoelectric Technology Co.,Ltd. offers all types of windows made from different materials. Special size and materials are also available upon request. In addition, we provide a variety of single layer or multiplayer anti-reflecting coating on optical windows. Specification of our optical windows as follow: *Material: BK7 or other materials *Length tolerance:0.01 *Width tolerance:0.01 *Center thickness tolerance:0.005mm *Surface quality:80-50 to 10-5 Scratch/Dig *Surface flatness:<lambda to lambda/20 *Parallelism<=1min -- 2sec *Clear Apenture:80% -- 100%