The Dixon DXTRADN is one of Dixon’s most popular whistles with is simple traditional design. It comes in a choice of brass or solid nickel body. The nickel used is solid cupro nickel (copper/nickel alloy) rather than plated, it’s the same material as is commonly used in your "silver" money. The brass has a sweeter tone than the nickel which might be, as the foundry tells us, because its 20% harder than the brass. Other than this the main difference being that the brass will inevitably tarnish faster. The nickellasts that bit longer!