Tested with a 130mm f5 reflector, sharp to the edge of a 1.2 degree field, very bright image, lightweight and mechanically rugged. No plastic on this unit. Rubber eyecup is soft and easily folded down. Eye relief is fine (I don't wear glasses). My only derate is for the undercut retaining ring which works to keep the eyepiece from falling out of the focuser, but tends to bind on compression holders, sometimes annoying.