German "Skeleton" Balkankreuz as used in the closing months of the war. These were very thin low-visibility insignia used in 1945, especially on jet fighters. Depending on the aircraft colour scheme, they could be black or white; this sheet provides them in both.
These decals are scaled to represent 30", 36" and 48" sizes in 1/300 scale. (They're also ideal for large aircraft in 1/600; equivalent to 60", 72" and 96" across.) The actual sizes are 2.5mm, 3mm and 4mm.