This celestron barlow lens increases the magnification of any 125 or 2 inch eyepiece by 25x 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