The F4F-3 Wildcat was the third monoplane to enter fleet service in the US Navy. It was powered by a Pratt & Whitney R-1830-76 radial engine rated at 1,200-hp. It had "stiff", i.e. non-folding, wings carrying four Browning .50 caliber machine guns. The F4F-3A has an R-1830-90 engine of the same horsepower, but with a single-stage, two-speed supercharger. Marine Air Group 21 on Oahu was equipped with F4Fs, some of which had just been delivered to Wake Island by Enterprise when the Japanese attacked Pearl Harbor.
You can learn more about the F4F in the following Osprey book: