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. 1 Large O-Ring for the M25X2 threaded section between the cylinder and the manifold, 1 stems with new seals and O-Rings, 1 stem retaining nuts with new O-Rings, 1 valve seat seal, 2 O-Rings to go on the DIN Insert only for use on the 232 Bar version. Please see Product Code TMSK for service kit for Beaver Sports twin manifolds.