Eyepiece Orion Sirius Plossl 6.3mm Orion Telescopes & Binoculars · Sirius Plossl 6.3mm Key specifications Focal length6.3 mm Apparent FOV52 ° Barrel size1.25" All specifications Elements4 About 6.3mm 52-degree Plossl eyepiece; Orion's standard 4-element Plossl line.