Airspeed Indicator, 420 Knots, US Navy
Here is an Air Speed Indicator as used in WWII-era and post WWII-era aircraft of the US Navy such as the F4U Corsair fighter (see illustration of the F4U instrument panel from its flight manual dated 1944 showing its location).
On this style of air speed indicator, speed between 0-200 knots is read on the outer pointer arrow clockwise along the outer perimeter scale, from 0-360 degrees. Once past 12 o'clock position, speed is then read from 200 knots to 420 knots on the inner pointer arrow along the inner scale.
The data plate is absent from this example, and it has a service date of 1955 stamped on its rear case. It is in reasonable condition given its age. Measures 3.25 inches diameter and ~ 3 inches deep.