This Marlin manufactured rear sight assembly is for the model 89C semi-auto rimfire rifle and is in very good condition with light wear.   The rear leaf is approx. .335" high and has a .060" wide groove, the elevator measures approx. .050" thick. The model 89C uses long rifle ammunition. (file photo)

Note: Marlin model 89C rimfire rifles with the following year/serial number have been observed with this part: NSN