Engineered to provide a comfortable 82° field of view, the Celestron Luminos 31 mm Eyepiece can be used with both low & high power telescopes. This 2? (5 cm) optical piece is multi-coated & has a 6-element configuration to produce sharp & clear views. It being parfocal, astronomers can swap the Celestron eyepiece during their observational sessions without additional focus adjustments.