Filter for observations of deep-sky objects. Barrel diameter: 1.25". This filter is perfect for observation of faint and low-contrast deep-sky objects. Levenhuk Ra UHC 1.25" Filter is able to suppress light pollution and enhance the contrast of the image from 2-5% to 10-50%. These features make it perfect for observing nebulae and other deep-sky objects. It has a barrel diameter of 1.25" so you can use it with any manufacturer's telescopes.