For sale is an Ariel 1 office stool by QOR 360, an innovative company making high-quality, back- and posture-healthy office seating and furniture. Sells for $445 + shipping, new.
From the manufacturer (4.8-stars, 63 reviews):
"Designed by our founder, Dr. Turner Osler, the Ariel 1.0 is the original chair that is loved by many around the world. It has our original Red-Rocker technology allowing the seat to move in all directions, engaging the core, improving posture, and relieving back pain. Award-winning design with a comfortable seat perfect for all-day active sitting. The Ariel 1.0 makes sitting healthy while looking damn good doing it."
See their site for additional details:
https://qor360.com/products/the-ariel-active-chair-qor360?variant=47203132277012