Red Devil is a mid-season apple, notable for its distinctive red flesh.
The flesh is white as with most apples, but stained with red which grows inwards from the skin. This is a characteristic sometimes seen in in its parent, Discovery, but much more obvious in Red Devil. It is currently probably the best flavoured apple with a red-flesh - although there are several other apple varieties which have a far more pronounced red-flesh than Red Devil, they are generally of very poor flavour.
Red Devil is a popular garden apple variety in the UK, often grown for its attractive pink-coloured juice.