Cheap And Discounts Optical Protective Windows HT1940 Plano Parallel Substrate Diameter 12.7mm Thickness Center1mm UV Fused Silica Coated Coating Wholesale. Buy Directly From Merchant Sun-Optics Precision Components Store. Enjoy ✓Free Shipping Worldwide! ✓90 Days Buyer Protection. ✓Easy Return. ✓Money Back Guarantee.