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