Sky-Watcher Field Flattener for Esprit-120

An optically-matched M48-fitting doublet field flattener for Sky-Watcher's Esprit 120 ED PRO triplet refractor. 

The M48 fitting provides a large clear aperture to reduce halation and a precision thread ensures the triplet and doublet lens groups are precisely aligned on the optical axis perpendicular to the image. 

When used with the field flattener the Esprit-120 ED PRO's imaging circle is 44mm.