Compatible with their Pf-65 and Pf-65 Ed Ii series, Pf-80 series, and Pf-100 series spotting scopes plus just about any telescope that accepts 1.25"" eyepieces, the Pentax Smc Xw 5mm Eyepiece produces a high magnification for examining details, whether you use it for astronomical or terrestrial subjects.Using low-dispersion lanthanum glass with a eight elements in five groups lens configuration and antireflection multicoatings, views through the eyepiece are crisp and bright with high resolution and minimal distortion. The spacious 70 Degree field of view and exceptional 20mm eye relief ensure maximum comfort for long-duration use..