All the necessary component parts required to have a complete service performed on all types of Beaver single outlet cylinder valves. All O-Rings and parts subject to any wear are replaced by a SCUBA Diving technician at each routine maintenance service, ensuring that cylinder vales remain in perfect operational condition. All O-Rings are manufactured from high quality Viton, suitable for use with Nitrox in addition to normal breathing air. Please see Product Code TMSK for service kit for Beaver Sports twin manifolds.