Used most commonly for certain Cameras and Binoculars. Thousand Oaks Optical (TOO) solar filters, the leading manufacturer that has been making safe solar filters for 35 years. Safely view the sun anytime, including during all phases of an eclipse with TOO solar filter sheets, lens filters, glasses, or viewers. TOO's exclusive high quality substrates provide superior safety features, sharper solar images, and a pleasing orange solar image. All products meet CE requirements. Only TOO has CE and ISO certification. Safe for unlimited visual and photographic use. Transmission: 1/1,000th of 1% (Optical Density 5). TOO products were exclusively chosen by NASA for use aboard the Space Shuttles. Other professional users include: ABC, BBC CBS, NBC, CNN, NOVA, The Discovery Channel, National Geographic, and most major universities and observatories throughout the world. TOO uses the latest technology for manufacturing and developing new products. Tens of thousands of their solar filters and millions of their solar eclipse viewers are used world wide.