The single's A-side, "United", was called "one of the first electropop singles" by Jon Savage., while the B-side, "Zyklon B Zombie", has been seen as a parody of punk rock music. "United" featured a minimal drum loop and synthesizer pattern with uncharacteristically positive lyrics, while "Zyklon B Zombie" featured little more than growling, distorted vocals and bass guitar with a frenetic guitar solo. Both tracks were later released on the CD version of The Second Annual Report.
The original pressing by Industrial Records had cream centre labels with very blurred Death Factory Logo and picture sleeve. After approximately 20,000 sales, re-pressing was taken over by Rough Trade and the single was re-cut with messages scratched in the centre: 'Salon Kitty' on the "Zyklon B Zombie" side and '437 666 OTO' 'RE-CUT 4 NOV 79' and '20,000 DOWN' scratched on the "United" side. The centre section of "Zyklon B Zombie" with Cosey Fanni Tutti's guitar was cut extra loud also as an improvement upon the original version. This version still had the cream/white labels with blurred Death Factory logo. Some were sold without picture sleeves, though not many.
A third pressing was in white vinyl (1,000 copies) and clear vinyl (1,000 copies) and features around two minutes of rain and train sounds at the end of side two.