William Optics Swan eyepieces are super-wide-angle designs with 72° apparent field of view.
They use simple but sophisticated five-lens optical systems for generally higher contrast than the more complicated optical designs used in some other SWA eyepieces that use up to eight lenses.
All lenses are fully multicoated for high light transmission.
Lens edges and internal field stops are blackened to reduce internal reflections and improve contrast.
The rubber grip ring is useful for safer handling of the heavier 2” eyepieces in cold weather when wearing gloves.
The eyepieces have soft roll down rubber eyecups for eyeglass use.
They are remarkably good all-round eyepieces when used with telescopes with focal ratios up to f/6 and above.