TOPIC:

I've certainly used "Scotch-Brite" pads. Went through a ton of them prepping my glider for paint. Outstanding sanding performance but I preferred to use wet paper instead for this project for a number of reasons. Mostly because I'm a sucker for punishment !. But primarily the greater control to remove material exactly where I need to. The "scotch-brite would be perfect perhaps for larger jobs where a polished finish wasn't the goal. :

I found using those pads with Mothers aluminum polish worked best for me. After working it the whole polishing surface gets covered with a grey sludge and gets worked both ways -
the abrasive pad and the chemical polish. It's flexible and easier than sand paper to get to those tight curvy spaces (no pun intended). I always cut off a smaller square from the big pad.

Scotch,

There is one on my second '79 Z1300 I bought last year as well. Never saw one before.
Was going to ask if anyone knows from which year and model they are, but now I see your post.
Looks like original to the '79 engine, but not sure, the bike was pretty messed with.

Here it is. It shows on the 1979 - 1980 A1 & A2 parts diagram on the Kawasaki website. It says it's a Canada model.

My Canadian 79 had the cover just off the bottom of your picture. Note #25 which are the block off plates.