In June 1943 the US roundel was replaced with the now iconic Stars 'n' Bars. Initially this had a red border, as on this sheet. This design was very short-lived, however; by August 1943 it was officially superceded, although in practice it did linger for a while after that.
These decals are scaled to represent 30", 36" and 48" height Stars 'n' Bars in 1/300 scale, or double those sizes in 1/600. The actual heights are 2.5mm, 3mm and 4mm, although obviously they're wider than they are tall.