tre kronor
"Tre kronor" translates to "Three Crowns" and is Sweden's heraldic national symbol with a long history. It is used in the coat of arms/logo of many governmental branches.
It consists of three three-peaked crowns in an equilateral triangle, with two on top and one in the bottom. The most common shape of the insignia is that of a shield, but the air force uses a round version on their vehicles, in which case there is a border in the same colour as the crowns. In its base form, the crowns are yellow on a blue fill. On military vehicles colourless versions are often used, with black (or dark grey) crowns and border with no fill, which is used on bright surfaces, or a white fill with black or transparent crowns and no border, used on darker surfaces. Very old army vehicles can be seen in pictures and museums painted with a rectangular version of the insignia in the latter colour scheme. However, the rectangular insignia was eventually dropped in favour of painting the Swedish flag instead.