Magnum (the US version) is a bittering hop, that has an alpha acid that typically ranges from 12-15.5% but can range from 10-15.5%. It has a beta acid of 5.5-8%.
It has aromas of Subtle Spice and Fruit. It is known for it's clean bittering value and quality, and is often a High Alpha Variety.
It is a great choice for use in IPAs, Lagers, Pilsners, and Stouts.
If you need a substitute we recommend Northdown or Northern Brewer.