Esa-Pekka Salonen: Sets

A performance of Sets by Esa-Pekka Salonen. Played by Equale Brass in a BBC Radio 3 broadcast on 15th April 1986.
I was unable to find any information about this work but vaguely recall that the title derived from tennis, hence the images. While looking for the information I was also intrigued to discover that Salonen has written a work for brass band - Apokalyptische Phantasie for Brass Band and Tape (1978). Never knew that before and certainly never heard it.