The classic square base is tried and true for stability and reliability. The 20 square inches keep off any wobbling or tipping while you pump the chair up and down in the 4 inches of variable height \n \nFeatures: \nSleek chrome finishing \nDurable square base with hydraulic pump \n \nSpecifications: \nAdjustable Height: 19 - 25.5" \nPump Stroke: 6.5" \nBase Size: 20" Square side \nWeight: 25lbs \n \nSome assembly is required. \nNote: Replacement bases are guaranteed to only fit salon chairs sold from IStyle Professional