I'm not sure. Maybe Greasy can confirm?Those are the ones that greasy put in a big order for a few years ago right? Those were killer.
The 600 GSM towel is so plush it's crazy. It is great for soft paints as even applying more pressure than needed, I can't see it scratching paint. haha But it won't remove compounds nearly as well per wipe as the lower GSM. Like their edgeless 350 or 385. The 500/600 are better for polishing detailing sprays, waterless & rinseless washes, and drying.
The Twistress holds a ton of water. It's isn't even comparable to the drying towel you just purchased. I can do my car and not have to wring it out so it can absorb more. They are great.