Courtesy of elbe from postcrossing forum
The current flag of the Republic of South Africa was adopted on 27 April 1994, at the beginning of the 1994 general election, to replace the flag that had been used since 1928. The new national flag, designed by State Herald Frederick Brownell, was chosen to represent the new democracy.
The flag has horizontal bands of red (on the top) and blue (on the bottom), of equal width, separated by a central green band which splits into a horizontal "Y" shape, the arms of which end at the corners of the hoist side (and follow the flag's diagonals). The Y embraces a black isosceles triangle from which the arms are separated by narrow yellow bands; the red and blue bands are separated from the green band and its arms by narrow white stripes. The stripes at the fly end are in the 5:1:3:1:5 ratio.
In blazons (a vexillological description using flag terminology), the South African flag is described as "per pall fesswise gules, sable and azure, a fesswise pall vert fimbriated argent, Or and argent."