Application: Astronomy telescope eyepiece is suitable for all astronomical telescopes (31.7mm or 1.25in interface). Used for astronomical observation of lunar , planets, nebulae, star clusters, dispersing nebulae and others. Large Field of View: Very comfortable for observation. Astronomy telescope eyepiece is not only with high brightness but also large field of view. Length: This is the 20mm or 0.8in length telescope eyepiece, superior performance for comfortable observation. Film Coating: This astronomy telescope eyepiece is with full multilayer coating, optical glass, provides maximum brightness, high clarity. Features: All metal, the bottom thread of this telescope eyepiece can be for adjustable 1.25in filter, for use with standard 1.25in interface telescope(not including) or filter(not including).