Ann and Nancy Wilson's performance of "Stairway to Heaven" from the Kennedy Center Honors is now available on iTunes -- but only for the next two weeks.

The Heart sisters closed the program with their tribute to rock icons Led Zeppelin after being asked by Robert Plant and Jimmy Page to sing their signature number at the gala, which aired December 26th on CBS.

That compelling performance received nearly four million views on YouTube in the few days following the telecast. Now it becomes a single, with proceeds benefiting the Kennedy Center Honors Foundation for the Arts.

It's one more highlight in a year that includes Heart's upcoming induction into the Rock and Roll Hall of Fame.