Mono Masters is a compilation album by The Beatles, and is an alternate, all-mono version of the album Past Masters. Mono Masters was originally a two-CD set included as part of The Beatles in Mono box set. The premise of this box set was to compile only Beatles material which was released or prepared for release with a dedicated mono mix (the set excludes later material mixed and released only in stereo, and material whose mono version was simply created as an equal mix of the two channels of the stereo version). As a result, the track listing for Mono Masters differs from Past Masters on the second half of disc two, omitting some later songs that never had a mono mix ("Old Brown Shoe", "The Ballad of John and Yoko" and "Let It Be"), and adding several songs released on stereo-only albums