The UltraBlock Filter is a narrow band transmission filter with very high (99.9%) blocking of Mercury and Sodium emission pollution bands, and very high transmission of critical Hydrogen Beta and Ionized Oxygen. It is most useful in areas of extreme light pollution like cities and busy streets. The UltraBlock Filter is particularly well suited for observing all plantary and emission nebulas.
Buyer pays shipping, insurance is mandatory. Paypal accepted if you pay the fees. Local pickup is fine if you are in the Tacoma, WA area. If buying multiple filters, feel free to make me a combined offer.