I’ve been around the strength biz a long time, and every time I figured I’ve “seen it all,” something crazy comes along and blows everything away.
Case in point: here’s a weird set of barbell plates, 45 lbs, yet in the approximate diameter of a 25 lb. plate as you can see in the lower right pic for comparison.

As you might expect, these unusual plates are quite a bit thicker than normal At first I thought they were simply two 25 lb. plates welded together, but that is not the case, they are, in fact, cast that way as is the “45” on the front, They have no other markings other than what is shown. I’ve never — and I do mean never — seen anything like these plates in any of the books, magazines, catalogs or price lists that I’ve come across.