Swedish air force roundels, suitable for 1937 through to the present day. Approximately 2/3 of each size are the traditional blue and yellow, with the remainder being a black outline form for modern low-visibility schemes. (Strictly speaking this should be a dark grey, but black's won out on practicality grounds, so apologies to the purists....)
These decals are scaled to represent 30", 36" and 48" roundels in 1/300 scale. (They're also ideal for large aircraft in 1/600; equivalent to 60", 72" and 96" diameter.) Actual sizes are 2.5, 3 and 4mm diameter.