The South African Mint released this "pattern" set prior to the release of the Third Decimal Series of South African coins. It features nine pieces - one cent to R5, which were all the coin denominations at the time plus the yet to be introduced R2 and R5. These were made to familiarise the manufacturers of coin-operated machines and other coin-related devices with the new coins, and so that the general public could gain familiarity with the new coin weights and sizes before the final designs were revealed. After the designs were revealed, the nine pieces were distributed in a mint set with the future designs printed on the cardboard cover. However, the pieces themselves intentionally do not resemble the final designs.
For that reason, even though the mint calls them "patterns" on the cover of the set, they are not actually patterns as they do not represent designs considered for production. The explanatory text also says that "These pattern pieces represent the diameter, colour and edge serrations only", i.e. the metal does not necessarily match the respective circulation coins as released later.
All pieces have the same obverse, and just one letter on the reverse - from A through J (no "I").
The cardboard packaging has a bilingual information sheet with the specifications of the pieces; the cover features the future designs - even that of the R5 which was not issued until five years later. The designs are preliminary and in some cases differ substantially from what was actually issued in 1990.