Abstract: Method for reducing the weight of molded golf club heads without changing their shape. Cavities of appropriate length and volume are created in the molded heads, extending from the rear face towards the front face thereof. Despite the cavities, the heads achieve a good restitution of energy, a good mass distribution, a low level of vibrations, and a good sound.

Abstract: A tennis ball conforming to the 1968 regulation of the International Federation of Lawn Tennis comprises a hollow elastic core and an improved cover bonded to the core by an adhesive mixture. The cover has a specific weight less than 0.22 g/cm.sup.3 and includes a proportion of relatively thick monofilament fibers such that the percentage-weighted average denier size of all fibers in the cover is at least 18. The cover improves the playing characteristics and the effective life of the ball.

Abstract: High performance one-piece solid molded polyurethane vulcanizate golf club heads having a unitary body including the entire front striking face and exhibiting specific properties by virtue of the vulcanizate; and golf clubs comprising the combination of said heads each with a golf shaft.

Abstract: A racket for tennis and other similar games, comprising a sensibly oval or pear-shaped stringing surface and an auxiliary element for maintaining the strings in a median plane at determined places, in which at least some strings are wound simultaneously around the frame and around the said auxiliary element.

Abstract: The invention provides tennis balls which comply in their behavior with the requirements of the "Rules of the International Lawn Federation" and which consist wholly or partially of a rubber based on natural and/or synthetic rubber which contains 15 to 50 parts by weight of a finely powdered aminoplast resin with a specific surface area of >5m.sup.2 /g. Suitable fillers for the rubber are urea/formaldehyde and melamine/formaldehyde polycondensation products. The tennis balls according to the invention can either have an internal gas pressure of 1.4 to 2.3 kg/cm.sup.2 (absolute) or they can be non-inflated, i.e. internally they have atmospheric pressure. The good behavior of these tennis balls is retained over an extended period of play. The tennis balls according to the invention are either provided with a textile or felt covering or they have no covering.

Abstract: A damping mechanism for implements such as tennis rackets, baseball bats and the like, comprising an elongated vibratable member formed of an elastomeric, energy-absorbing material. One of the ends of the vibratable member is attached rigidly to the implement at a point near an anti-node, with the longitudinal axis of the member concentric with or generally parallel to the longitudinal axis of the implement. The dimensions of the member are adjusted such that the natural frequency of vibration of the member corresponds generally to the vibration induced in the implement in use as a result of striking a game ball or the like.