Isokinetics Inc. Adjustable Back Exercise Ball Office Chair - Standard or (Exclusive) Tall Boy Frame Height - with 52cm Ball - Office size 60mm/2.5" wheels - w/Starter Pump and Ball Measuring Tape STANDARD HEIGHT ball chair frame with office size 60mm (2.5") wheels, which provide a smoother, quieter rolling experience versus 50mm (2") used on other brands. Our weight-bearing, adjustable seat back is ideal for work or home use. It can be adjusted from a firm lower back support to a comfortable laid back position. Search YouTube (isokinetics inc) for a video demo of this chair. PLEASE test sitting heights (see bullet point) at home before you choose between our Standard or Tall Boy frame SITTING HEIGHT: Measurements require ball filled to 52cm (with ball on floor, 20.5" measured straight up to a line level with ball top). Each person is different, but the Standard frame user height range is about 5' 0" to 5' 11". We recommend you test sitting heights at home before buying. In the frame, the ball top is 23.5" unsat on. Seated, a 135 lb person sits about 19.5" off the ground; 150 lb, 19"; 175 lb, 18.5" & 200 lb, 18". By comparison, basic solid seat chairs are 17" to 18" high PLEASE NOTE: Height adapters that add 2" (sold by other sellers) do not fit any model of Isokinetics Inc. brand ball chairs. Please choose between our Standard or Tall Boy frame height. CHAIR DIMENSIONS: 21"W x 22"D; seat back adjusts up/down from 32" to 34". Weighs 15 pounds IN BOX: Rolling ball base and adjustable back in solid black, 4 60mm (2.5") wheels, 2 of which are lockable, a reinforced black metal ball retaining bar, a 52cm Isokinetics Inc. branded ball, a small starter pump, our exclusive ball measuring tape, Isokinetics Inc. Contact and Warranty sheet, assembly instructions and basic exercise guide. We guarantee our ball will inflate to 52cm (20.5"). See our YouTube video on proper ball inflation (search isokinetics inc) WE GUARANTEE our chair frame AND ball for 1 year. We also guarantee our 52cm (20.5") ball will fill to its intended size. Read included instructions and watch our YouTube video (search isokinetics inc). Final ball measurement, with ball sitting on the floor, is 52 cm or 20.5" measured straight up from floor to the point level with the ball top. Call us if you have questions