C-Lock SYS-patented cover locking system is easy to use Covers snap on to base and can be interchanged C-Air SYS-patented Choice base and cover has air inlets for air flow Polyamide HIS (High Impact Strength)-fatigue resistant, torque rigid, weather and chemical resistant base material. Easy to clean UltraLight PU Double Skin foam fill provides comfort and durability Microfiber outer cover material 270mm x 123mm 230g