Vinyl grips on tubing prevent marring tub. Tube in a Tube construction for added strength. Tub must be 22in wide at center of tub. Take this measurement halfway down the wall and measure inside wall to inside wall dimension. Outside legs adjust from 18.5in to 20.5in. Seat depth is 20in. Although this item is universal, order R or L for bathroom configuration when possible. (Seat on left shown) Capacity 850 lbs.