This is left over from my Olympus film days, I forgot that I even had it. It fits on the eyepiece, gives magnification of 1.2x or 2.5x, enabling you to focus very precisely. It also swivels to either side once mounted. Fits on the Pentax K-5 and maybe some other DSLRs, but I'm not sure which ones. This one was repaired to like-new status by John Hermanson of Camtech a few years back, and I never used it after it came back. Price is $40 and that includes PayPal fees and Priority Mail shipping in the US.