This 1.25inch UHC filter is designed to improve the picture contrast of the subject Substrates: precise polish substrates, good parallelism and surfaces precise High contrast filter (UHC filter) is of light filter, it is more Significantly reduce light pollution, suitable for city and suburban observation Double-sided fine polishing and polishing process ensures high parallelism Coating: double-sided multi-layer coating, the backside increases the penetration film and reduces the reflect light Diameter: 1.25 " simply attached to the eyepiece, installed in a solid shells