In excellent as new unmarked condition, around $300 at most shops.
Manufacturers Description
• Eliminates field curvature in short, optically fast refractor telescopes, for sharper stars
• Designed for use with 400mm to 660mm focal length refractors with f/5 to f/7.5 focal ratios
• Preserves focal length attributes of the attached refractor telescope while flattening the field of view
• Compatible with 2″ focusers and requires 55mm of backfocus
