This is the supposed 'Holy Grail' of Abbey Road versions.
"Black Triangles" are 1st -generation CDs released by EMI-Toshiba in Japan, during the initial launch of the CD format, in 1983. The name is derived from the label design that was used on the CD. Most stayed in print for less than a couple of years (some, like "Abbey Road", **much** less), and in general, they're highly sought after because they are reasonably flat transfers of the Japanese master tapes used for each title. "Abbey Road" and "Wings Greatest" are LP masters, for example, have no noise reduction, and are very dynamic-- particularly when you compare them to the officially-sanctioned versions that British EMI released after 1986.