Orion 5188 1.25-Inch Jupiter Observation Eyepiece Filter The filter is set to screw onto a 1.25 eyepiece and the inner dimension is slightly smaller to accommodate the insertion of the compression ring into the casing. Helps reveal feature details of Jupiter easily in any telescope Significantly increases visibility of the main equatorial cloud belts Jupiter displays more surface detail than any other nighttime object except the Moon - make the most out of each view with this affordable filter Medium Blue 80A filter enhances contrast of Jovian features such as the Great Red Spot