Originally $99, Gaiam's Ergonomic Balance Ball Chair in charcoal is now on sale for $78.98. Enter $15 off $75 code EN8A to lower the price to just $63.98, one of the lowest prices we've seen. The chair includes a removable 52cm Balance Ball, an adjustable support bar, easy-glide casters, an air pump, and a desktop guide to get you moving. It's designed to strengthen core muscles and improving spinal alignment as you go about your daily office routine. Shipping adds $11.99 but there is no sales tax (except CA, CO, OH).