I have 2 pcs of Televue extension or adapter, label engraved as "Televue Nagler 13mm". One has label in green letters and one has black letters. I got it from package deal a few years back and never used, just sitting inside cabinets.So I am not sure what is it really for. Package is 2 pieces.
Main tube (each)
Length: 52mm (excludes male thread portion)OD: 50mmID:40mm
Male thread OD: 46mm
Filed under: Eyepieces & Accessories