Cockpit Panel Clock ACS-1(АЧС-1) for a Soviet MIG / Su aircrafts. These clocks have been designed to withstand speeds of Mach 3 / 1800 mph (2900 km/h) and altitudes of up to 100,000 feet (30 km). Built-in 27-volt heater ensures operation even at -60 °C (-75 °F).
eBay