Additional Details ------------------------------ Product description: The SMA design is an improved version of the Kellner eyepiece. SMAs are very good, economical, general purpose eyepieces that deliver a wide apparent field, good color correction and an excellent image at the center of the field of view. The eyepieces are fully coated for high contrast. This 10mm eyepiece features a 6mm eye relief and a 52 degree apparent field.