The 2" diameter barrel 68° Series 28mm Eyepiece from Explore Scientific is a wide-field telescope eyepiece designed for detailed close and deep-space observation. It uses low-dispersion, high refractive index glass with anti-reflective fully multi-coated optical surfaces to ensure bright, high-contrast images with true color transmission across the entire wide field of view. Its wide AFoV and long eye relief makes this eyepiece ideal for comfortable viewing for extended periods with or without eye glasses. The contrast is enhanced by a fold-down rubber eyecup that prevents stray light from leaking into your eye. The eyepiece features a textured surface for a sure-grip when changing it out, and it is argon-filled for water and fog-proof performance when used in extreme temperatures and climates.