Bill's referring to a rubber weightbelt used by freedivers.
They can be real handy but also have their downsides when used in a scuba application.
Normally you over tighten these around your hip bones (lower than you would a scuba weightbelt) and they stay that way even at depth. So no constricting belt on your belly, and no adjusting belts at depth.
There's 3 types of buckles. Your wire buckle, quick release buckle, and Marseille buckle.
The wire buckle isn't quick adjustable. You have to thread through triglides at either end to adjust the length. So if you change exposure suits or weighting, you'll be rethreading that each time. To fine tune it to the right length you may have to thread it, try it on, take it off, repeat.
The quick release is exactly the same as your standard weight belt, however plastic buckles tend to pop open or takes a lot of force to close shut, because the rubber likes to rebound back. Metal buckles can eat into your rubber if they're too sharp.
The Marseille belts are usually skinner than 2in, and sometimes too thick for your usual single-slot vinyl bullet weights. So you have to use Tin Man's pinch weights or your 2 slot lead bricks.
All belts quick release easily, but if you're using more than 20lbs they tend to sag a bit on dry land and even in the water if you're vertical, because the rubber isn't rigid enough. Between brands, there is also a wide variety of rubber, thickness, and elasticity that can exacerbate these issues.
I personally don't see a huge benefit to work through these unless I'm freediving, so I don't use them for scuba. YMMV