A clutch release bearing having a fixed portion including an inner support tube and an outer body concentric therewith which defines a control chamber capable of being supplied with a fluid and housing an axially movable tubular piston supporting a drive member engageable with the diaphragm of the clutch, wherein the support tube axially projects beyond the outer body. The diisocyanate cross-linking agent cross-links the hydroxy terminated polybutadiene to form an elastomeric binder that contains the particulate oxidizer. To produce a leakproof accumulator arrangement economical to produce, a gap opening between the casings extends up to a point at which the casings are positioned together in a coaxial manner, and a disk valve is provided as a valve for controlling the supply and discharge of the medium in the opening. In one embodiment, a conductor is wound about the member. A method of making a golf club head comprises making a wax model of the hollow main body having an opening, wherein in order to prevent deformation of the wax model during making a casting mold, the wax model is provided with a brace which extends across the opening and protruding walls which are disposed on the inner surface of the wax model and extend backwards from the opening.