Paul McCartney has something special planned for the 50th anniversary of Wings’ Band On The Run.

An expanded anniversary edition will be released early next year, including “underdubbed” mixes of nine of the album’s 10 tracks.

What exactly is an ‘underdub’? We’ll let McCartney himself explain: “When you are making a song and putting on additional parts, like an extra guitar, that’s an overdub. Well, this version of the album is the opposite, underdubbed.”

The two-disc set also includes two Polaroid posters by the late Linda McCartney.

Band On The Run 50th Anniversary Edition will be out Feb. 2nd.