This is the excellent, much sought after (now discontinued) Spectra Astrosystems SureSharp knife edge focuser for an Olympus OM-1.I bought this new from them several years ago, and have never used it.It is flawless, not even a fingerprint on it!
$150.00 Buyer pays shipping of choice
Will accept check, cashiers check,
or money order. (sorry no PayPal)