This Celestron Barlow lens increases the magnification of any 1.25 or 2 inch eyepiece by 2.5x, and makes a useful addition to your astro inventory. The 4-element multi-coated apochromatic optics are tuned to produce a flat field of view without light loss or false colour, and the lens is threaded to accept 2 inch filters. The finish is excellent and practical: A hard-anodised aluminium housing with rubber grip and practically-sized thumb-screws - easy to operate, even with cold fingers or while wearing gloves.