More aperture for astrophotography and vistual: provide good image with high contrast; ED glass means visible colour aberrations are reduced to minimum with sharp image; all lens surfaces have been provided with multi coated to reduce
For astrophotography; sometimes more focal length is required in order for them to be seen at a reasonable size in the image especially for compact objects; there is also no shadowing apparent on small image format camera chips for big plus
Larger diameter has more scope for lenses: 2 inch diameter allows to insert 2 inch eyepieces into this barlow with double magnification; the large lens diameter also means you will notice no shadowing in the image;
2 inch Kellner wide field eyepices with comfortable viewing position; Kellner eyepieces are a further development of the classical Kellner design; they have a more comfortable viewing position and better off-axis definition
High-level craftmanship the lenses are multi-coated and have blackened edges and a blackened interior; offering the budget-conscious amateur stargazer an excellent alternative to more sophisticated and expensive eyepieces