McKesson Contoured Seat Cushion 24 W X 18 L X 3 D Inch Molded Foam (1065587_CS) 4/CSWaterproof, low shear stretch nylon cover allows air to pass, but resists fluids for lasting breathability, comfort and durability to withstand daily use and patient incontinence. Specifically designed to optimize pressure relief by allowing user's pressure points to "immerse" into the gel infused, visco foam top layer Molded leg troughs promote thigh alignment and postural symmetry Raised front ridge to promote proper positioning and control sliding