The Isle of Man has its own circulating coinage, which is used in parallel with the British Pound Sterling; it also issues an extensive range of commemorative coins for collectors, as well as bullion coins in a variety of formats and designs for investors in precious metals.
One of the sizes used is the very large five ounces of silver format, abbreviated as 5oz Ag, where Ag comes from the Latin word for silver, Argentum. The coins are considered Non-Circulating Legal Tender (NCLT) because they are "premium" editions released at prices much higher than their bullion value.
This coin is the first silver five-ounce piece in the extensive Angel range depicting Saint Michael slaying the dragon, which is issued since 1984. The original Angel was a gold coin introduced in England by King Edward IV in 1465 as a new issue of the Noble. Based on a French coin, the Angelot or Ange, its name was derived from the representation of the Archangel St. Michael. The image of the Archangel Michael slaying the dragon was thought to bring good luck and health and was traditionally given to sufferers of the disease the "King’s evil" or scrofula, in a medieval ceremony intending to cure them with the "royal touch".
It is usually said that modern Angels are legal tender but without a fixed face value, like the Krugerrand or Mexico’s Libertad which are legal tender to the value of their precious metal content. However, according to the various Currency Determinations by The Treasury of the Isle of Man authorising each issue, under section 6 of the Currency Act 1992, the "Angel" denomination is equal to 5 pounds in face value, with fractions or multiples divided or multiplied as required by the fraction or multiplier shown on the reverse of the coin - hence, the five ounce coin a nominal face value of £25 (twenty-five pounds). | 
Search for Isle of Man: Silver Five Ounces 1995 Angel on eBay 