Reddit mentions of Roll About Stool

I have a seat that is sort of like a 3 wheeled bike seat that I use. it looks like this they don't have it at that site, its out of stock, but that's what it looks like, and is height adjustable. I like that I can fully sit down on it, or do the "sit/stand" position where you're almost standing but with weight on the seat, and has a decent size seat.

My knees are trashed - I have a tkr on one, so kneeling is out.