Abstract: In construction of a vibration absorber for a racket, a mass is indirectly supported by a visco-elastic member arranged within the grip or the yoke of the racket via an elongated interface so that resonant swing of the interface on receipt of vibration from the head of the racket should cause deformation of the visco-elastic member for thermal diffusion of vibration energy. The visco-elastic member is sandwiched between two elongated leaf springs. One end of the leaf spring is mounted to the wall of the racket handle and the other end of the leaf spring supports the mass. By proper choice of the component, vibration in a specified frequency range can be selectively damped so as to match vibration characteristics of rackets of various types.

Abstract: In production of a core-shell type golf club head, a thermoplastic synthetic resin core preferably of 15.degree. C. or higher glass transition point is used as a substitute for the conventional rubber air bag for stable and reliable shaping of an FRP shell even under the room temperature condition and beautiful moulding of the shell through softening and inflation of the core at heat pressing, thereby avoiding air void generation and layer separation in the FRP shell.