Of all the decimal Proof Sets the 1972 is the most important because none of the coins were issued for circulation, except for the crown that is. That means if you need the 50p, 10p, 5p, 2p, 1p or the 1/2p the only way you can get them is from the Proof Set. Plus of course you also get a Proof cupronickel Crown and the Royal Mint medal of 1972 in the original packaging.