Stereo/Mono promo copy. There really hadn't been anything like this before, and nothing but pale imitations since. Of course, there haven't been any musicians like John Bonham and Jimmy Page, or vocalists like Robert Plant. Not that this is the very best thing they did together, but it's surely their hardest-rocking single. This amazing promo has an edited version (labeled as "Edited Short Version") of the album cut that's about a minute shorter — very skillfully done, so that by the end I couldn't think of what parts were missing! It's a rarely seen version of the promo that has a 2-tone color design for the Stereo side (red and light blue). Not that I don't like hearing the whole thing, too, but when you're in a hurry, a "Black Dog" that's 4 minutes instead of 5 can really shake your world! Note: This beautiful promo 45 comes in a vintage Atlantic Records factory sleeve. It has pristine Mint labels and audio... both sides! Take a listen to the mp3 snippet I made of the Mono side.