Second Crosshair in Cockpit mode

[Panzergranate]

The back up gunsight is also found in the Zero in Battlestations Pacific and a few other simulators.

It is a back up incase the bulb fails in the reflector gunsight, though it isn't aligned with the guns as accuarately as the reflector sight. More akin to the vane sights on a pistol.

Ironically, on the Soviet LaGG-1 and LaGG-3 fighter the "gunsight" was a crude circle painted onto the windscreen on the majority of the type, Things were that desperate back in 1941-1942.