The Australian one ounce silver piece (abbreviated as 1 oz and designated with Ag for "silver") is a bullion and commemorative coin format. Uniquely, in Australia there are two mints 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 Silver Kangaroo coin range was introduced in 1993 by the Royal Australian Mint; subsequently, the Perth Mint also started issuing Kangaroo bullion coins. The coins have legal tender status in Australia and are one of few legal tender bullion silver coins to change their design every year. This and their limited annual mintage may, unlike for many other bullion coins, raise their numismatic value over the value of silver used.
This coin is the first silver coin in the series, and has high relief on a thick blank (with smaller diameter than the usual silver ounces).
The mint says about it:
The Perth Mint is pleased to announce an unprecedented new addition to the renowned Australian Kangaroo bullion coin series. Previously only available in pure gold, it now includes an annual silver release for collectors!
The exciting new coin is struck from 1oz of 99.9% pure silver in proof quality. For outstanding impact, the coin is made with an extra-deep blank to accommodate its superbly detailed high relief design portraying boxing kangaroos in Australia’s outback. | 
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