This is a spotting scope eyepiece adapted to a 1.25" eyepiece with a screw-on adapter. it should work with all other Nikon RAII series spotting scope eyepieces - not newer versions though.
Excellent quality, about 50 deg+ AFOV, lighter than a Siebert 7mm EP! Purchased for $50 a few months ago. Only used it one night. I DON'T KNOW HOW MUCH IT'S WORTH, BUT OFFER ME A REASONABLE PRICE. i accept paypal and money orders. i will trade it straight up for a astrozap 9.25 SCT dew shield. thanks.