Sign up for PayPal; the fast, easy, and secure way to pay online. This filter is a Neutral Density Filter. The Borosilica base substrate is coated with a thin film of a metal alloy that transmits light uniformly as a function of wavelength. This filter is anominal Optical Density of 1.6, or 4% transmission. The filter will act like a 5 stop reduction in exposure. The goal is to make a filter that has no color, but stops or attenuates the light to a specific degree. The filter specifications follow: Nominal Density 1.6 (actual 1.6+-0.15 through the visible, and near IR. Size is50X50mm. by 2.0mm thick. If you don't find what you want with a simple search in my BJOMEJAG EBUYER STORE, try a wild card search by using an asterics after the wavelength. If you are still not finding a good match, follow my links to Omega's Build a Filter. With a note to the effect that cosmetic seconds are acceptable, you will be surprised how economical an exact match can be. Be sure to add me to your favorites list! Powered by eCRATER . List your items fast and easy and manage your active items. On Feb-27-13 at 23:41:24 PST, seller added the following information: FREE! Sellers: Add a FREE map to your listings. FREE!