Orion 7129 2-Inch Telescope Eyepiece Parfocal Rings, Set of Four Make a set of non-parfocal 2" telescope eyepieces parfocal with a Set of 4 Orion 2" Parfocal Rings Increase observing efficiency easily and affordably! Eliminate the need to make focus adjustments when changing telescope eyepieces Each black anodized aluminum parfocal ring features three equidistant setscrews for secure attachment to any 2" telescope eyepiece barrel With parfocal ring equipped telescope eyepieces you can change magnifications quickly