The Most Versatile Active Sitting Disc Available This self-inflating Therm-a-rest sit disc is perfect for your active sitting and exercise lifestyle. This multi-functional balance disc has various uses, from creating an instable sitting or exercise surface to injury rehabilitation and sitting pain prevention. Another great FUNctional Fitterfirst tool! -Great for travel, very compact when deflated. -Over-inflates to be used as a bolster for exercise or sitting. -Provides relief from nerve and muscle conditions such as sciatica