Fully multi broadband coated and all optical glass lenses maximize the light transmission and minimizes internal reflection and maximizes contrast 40mm focal length and long eye relief,very convenient for viewing Long eye reliefFeatures for any 1.25'' diameter telescope,standard thread to fit a filter Plossl design delivers sharp images;highly achromaticdesign with good color correction and contrast Black anodized aluminum housings;internally blackened to eliminate light scattering and contrast. Black anodized aluminum housings;internally blackened to eliminate light scattering and contrast