r/guns – Buddy found this old iron sight in a barn in North Dakota. Any ideas what it’s from?

My buddy found this on a farm in North Dakota while researching his family history. It appears to be some sort of sliding adjustable iron sight often found on rifles, however I have no idea what specifically it was from. The distance / elevation scale don’t seem to be in a scale that one would find on a rifle, maybe in tens of meters or tens of yards? Or maybe it was a retrofit for a black powder rifle, or possibly an old toy?

Edit: u/Wald0_17 likely guessed it, it’s from a 1916 Spanish Mauser