Manifold Pressure meter - Yak 52
Working when removed.
The Yak's M14-P motor is lightly supercharged so it's possible to see overboost at sea level on takeoff.
The metric units of pressure were unfamiliar to US Pilots, so somebody decided that the Russian word below the needle (starting with a Cyrillic character that looks like an H) should be pronounced 'Potatoes'.
Ever since then Yak pilots can be heard discussing power settings as '7 potatoes and 70 percent' - or something like that.
In unmodified, factory-equipped Yak 52's, this Manifold pressure instrument only appears in the front cockpit, it being assumed that any Russian Instructor worth his salt would be able to know the manifold pressure without needing a gauge.