This is a US acetate that was auctioned in January 2005. Because it's a US acetate, it can be assumed that it's simply the standard US single mix (RS1). However, the running time of 3:05 is shorter than the US single which is 3:10. This could simply be an earlier fade or possibly a speed variance of some machine used in processing this disc. The 3:05 designation seems to also be noted on the acetate seen here.
The notation '5-5' would seem to indicate that this is indeed the US single mix. The release date in the US was 5 May 1969.
See the other "Get Back" acetate - here
See an additional "Get Back" acetate
THE BEATLES ONE SIDED TEST PRESSING GET BACK
Item location: Manchester, Lancashire
THIS IS A ORIGINAL 1969 ONE SIDED APPLE LABEL TEST PRESSING OF THE BEATLES U.S.A. RELEASE GET BACK IT IS ON A PLAIN APPLE LABEL AND THE PRINTED WORDING " APPLE RECORDS INC, 1700 BROADWAY N.Y. 10019 U.S.A. " AROUND THE LABEL RIM WRITTEN IN PEN BY HAND IS THE WORDING THE BEATLES GET BACK 3-05 (THE LENGTH OF THE TRACK ) AND THE RELEASE DATE 5-5 IN THE RUN GROOVE IS THE MATRIX NUMBER S-45-46843-A-7 APP CUST 2490 ALL LETTERING HAS BEEN ETCHED THE LABEL IS CLEAN THE VINYL IS VERY GOOD PLUS A FEW VERY LIGHT MARKS PLAYS EXCELLENT COMES IN ORIG INAL BEATLES ON APPLE USA `SLEEVE