With unsurpassed optical clarity and a short focal length, the XW 3.5 offers a 70 degree field of view for easier viewing. All of our eyepieces are constructed with a high-refraction, low-dispersion lanthanum glass that consistently delivers bright, high-resolution images with minimal distortion. In addition, all XW series eyepieces are built to JIS Class 4 weather-proof standards which increases their durability.