Configure your Evolution Stability Ball Chair to fit your own style with the Special Edition Sherpa Stability Ball Chair Kit, which includes the “Sherpa” Cozy Cover and your choice of one non-marking EVO ICE casters in five colors - all at a discount! Premium Evolution Chair Kit includes: - High quality height adjustable base (risers included for additional height), anti-burst stability ball and pump. - The “Just Move It” Poster featuring a series of 34 exercises to keep your back strong and aligned. - Premium smooth rolling and non-marking EVO ICE casters in choice of five colors. - A selection of Ball Chair Slipcovers in solid colors and designer patterns.