SoundBoard

According to Beatle folklore, promotional copies of their unreleased 1969 Get Back LP were distributed to radio stations in the United States.
In fact, no promotional copies of the album were issued, although many radio stations aired tapes which were in circulation at the time. Some stations (such as WBKW in Buffalo, and WEBN in Cincinnati) aired an undocumented mix of Get Back (available only on an obscure bootleg entitled O.P.D.), which mirrors the "final" track listing of the LP, as documented in The Beatles: Recording Sessions. (continued) -vigotone.com

This tape is significantly different than the "final" mix, which is widely available on various illicit records.  It's noticeably less processed than the other both in terms of editing and the use of reverb.  It also includes an extra performance of "Get Back", and a cover of Jimmy McCracklin's "The Walk".