Lumicon Dust Seals keep dust, moisture and insects out of your Schmidt-Cassegrain telescope (SCT). The glass is a plane-parallel polished surface that passes more than 98% of all visible wavelengths, with no noticeable internal reflection or aberration. The LF3165 threads onto the 3.28" x 16 male rear-cell threads of the Celestron's 11 - 14" SCTs, and presents the same threads for accessory attachment.
This Lumicon filter has a clear aperture of 67.2mm (2.65"). Item weight = 2.9 oz.