The Saab J 21 was an unusual Swedish-designed fighter of WWII vintage, first flown in 1943. Its pusher propeller — driven from behind the cockpit — was a deliberate choice that kept the nose clear for forward-firing armament, but it also meant Saab had to develop the world's first cartridge-powered ejection seat, since a pilot bailing out would otherwise be thrown straight into the propeller.

This aircraft, individual number 21311, is one of only two surviving J 21s in Sweden — the other is on static display at Flygvapenmuseum in Linköping, which also holds a J 21R mockup. The red nose, red spinner and red individual letter "A" on the tail boom indicate its division within the wing. The yellow "15" beside the roundel marks it as belonging to F15 — Hälsinge Wing, based here in Söderhamn. The small golden leaping goat is Hälsingland's provincial coat of arms.

The aircraft is displayed with its ejection seat partially extended from the cockpit, seat dummy included — a nod to the seat's own story: it was reportedly found in the forest by a farmer after a Hälsinge Wing pilot made a successful ejection.