Kore Everyday Wobble Office Chair - Standing Desk Stool, Better than a Balance Ball for Office - Black Vinyl GREAT FOR THE OFFICE - Gently rounded ergonomic base allows you to move and flex without leaving your seat STAY ACTIVE - Exercises legs, back, and abdominal muscles while you "actively sit" SOOTHING - Relieves soreness and stiffness and allows mobility while you sit FITS A VARIETY OF USERS - Adjustable seat height from 18" to 25" GREAT OFFICE GIFT - Improves productivity, decreases back pain, while helping you stay focused for longer periods of time thanks to "active-sitting"