If you observe from highly light-polluted sites, or if you want the maximum contrast enhancement for observing faint emission nebulas from areas of moderate light pollution, an Orion UltraBlock filter is for you. UltraBlock filters block all forms of light pollution. They reject wavelengths from incandescent and fluorescent lighting, which wideband filters can't stop. Extremely high (99.9%) blocking of critical mercury and sodium emission bands and very high transmission of hydrogen-beta and ionized oxygen wavelengths result in the highest contrast gain of any competing light-pollution filter.
Filter is in excellent condition with no visible dust or spots on optical surfaces.
I'm asking $95 USD and will sell to first serious offer. I will accept payment by cashiers check, money order, or paypal. Upon receipt of payment I will pay for shipment by USPS priority mail to anywhere in the United States.