Enhance the stability of your chair with the Vibram® Ball Feet rubber tips. The 45 mm size is compatible with the Chair One (made from 2015), Chair Two, Chair One Mini, Speed Stool, and Chair Zero. The 55 mm size is compatible with Chair One (re), Chair One High-Back (re), Chair One XL, Swivel Chair, Sunset Chair, Savanna Chair, and Bench One.