The Australian one ounce silver piece (abbreviated as 1 oz and designated with Ag for "silver") is a bullion coin format. Uniquely, in Australia there are two mints independently authorised to strike legal tender: the Royal Australian Mint (which also makes the country's circulating coinage) and the Perth Mint which only makes collector and bullion coins, as well as other bullion products.
The Australian Koala series by the Perth Mint comes in several sizes and compositions: 1 kg silver, 5 oz silver, 1 oz silver numismatic (proof, high relief) and 1 oz silver bullion. The Royal Australian Mint also issues silver Kookaburra bullion coins.
The reverse design changes every year, always featuring a koala - one of the most famous and distinctive animals native to Australia. The silver ounce coins have a face value of 1 dollar, but this is only symbolic - as the bullion value of their precious metal content is much higher. The coins were .999 fine silver until the 2018 edition, which increased in purity to .9999 silver. The overall weight is slightly more than an ounce, so that the pure silver content is exactly 1.000 ASW (troy ounce Absolute Silver Weight). | 
