Nice mounted air-spaced achromatic glass telescope objective. Both elements are AR coated. Clear lens diameter of 90mm with a focal length of 900mm (F/10). Front barrel diameter is 90mm (ID) and 98mm (OD), rear barrel is 90mm (ID) and 108mm (OD). The entire assembly is 80mm long. These are brand new and will make a great scope! Or get 2 for a binocular scope. New
