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 part of the long running Angel bullion series, which was issued by the Pobjoy Mint until 2016, and the Tower Mint later.
It is usually said that 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 size is equal to 25 pounds. | 
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