Orion 8884 3.0mm Edge-On Planetary Eyepiece;

Edge-On Planetary eyepieces bring flat-field performance to solar system viewing in the form of three high-magnification focal lengths. Each employs a sophisticated 7-element lens design reminiscent of exotic, high-priced oculars to provide a sharp focus all the way to the edge of their wide 55-degree apparent field of view. The barrel distortion and field curvature aberrations common in standard eyepiece designs are virtually gone. Edge-On Planetary eyepieces let you push the power, whether you're canvassing the lunar terminator or studying the Jovian cloud belts. The 7-element optics are fully multi-coated for high light transmission, and each eyepiece has 20mm eye relief for viewing comfort. Other nice touches: blackened lens edges, pop-down rubber eyeguards, and barrels threaded for 1.25" filters. Barrel diameter: 1.25".