A rubber composition for a hollow ball includes a base rubber and an inorganic filler. A weight reduction rate TGA.sub.650 from room temperature to 650° C. and a weight reduction rate TGA.sub.850 from room temperature to 850° C. of the rubber composition are measured under an air atmosphere by thermogravimetry conforming to JIS K0129. The weight reduction rate TGA.sub.650 of the rubber composition is not less than 63% and not greater than 99%. A difference (TGA.sub.850−TGA.sub.650) between the weight reduction rates TGA.sub.850 and TGA.sub.650 of the rubber composition is not less than 0% and not greater than 7%. A hollow ball 2 includes a hollow core 4 formed from the rubber composition.

A DPS (dual pressure system) sport ball incorporating a special, environment friendly casing that forms an exterior surface of the ball, which is bonded to a multiple lining layers to form a laminated sheet. The laminated sheet is sized, printed, and cut out into specifically designed panels using highly optimized and automated specifically developed machines. The panel cut outs are stitched together using a special stitching machine and a specific, compatible bladder is incorporated in the ball. The partially machine stitched ball is then finally closed by manual stitching and the seams are protected with a special adhesive. Resultantly, due to unique construction materials, their unique arrangement, innovative technology, and highly automated manufacturing processes, the DPS sport ball has advantageous durability, playability, controllability and excellent flight characteristics. The DPS sport ball qualifies under the international standards of match/professional balls at a very competitive price.

A DPS (dual pressure system) sport ball incorporating a special, environment friendly casing that forms an exterior surface of the ball, which is bonded to a multiple lining layers to form a laminated sheet. The laminated sheet is sized, printed, and cut out into specifically designed panels using highly optimized and automated specifically developed machines. The panel cut outs are stitched together using a special stitching machine and a specific, compatible bladder is incorporated in the ball. The partially machine stitched ball is then finally closed by manual stitching and the seams are protected with a special adhesive. Resultantly, due to unique construction materials, their unique arrangement, innovative technology, and highly automated manufacturing processes, the DPS sport ball has advantageous durability, playability, controllability and excellent flight characteristics. The DPS sport ball qualifies under the international standards of match/professional balls at a very competitive price.

A bag for storing tennis balls has an hermetic enclosure formed of flexible material, an opening larger than a tennis ball into the enclosure, the opening having a hermetic sealing zipper by which the opening may be opened and closed, and a flexible tubing from outside the enclosure through the flexible material, the flexible tubing having an open end adapted to engage an air pump, and a one-way valve adapted to admit air into the enclosure and to prevent air from exiting the enclosure through the tubing. Tennis balls placed into the bag are placed under pressure higher than the pressure inside a tennis ball by closing the opening by closing the hermetic sealing zipper, engaging an air pump to the open end of the flexible tubing, and operating the air pump until a predetermined pressure is established in the bag.

An overcap for a container for storing at least one tennis ball, the container extending along a longitudinal axis and having an open end. The overcap includes a body adapted for removably attachment to the open end of the tennis ball container. The body includes a peripheral rim for engaging an outer surface of the container at the open end, and a lip projecting from the peripheral rim toward the longitudinal axis. The peripheral lip extends over a portion of the open end of the tennis ball container. The lip defines a first opening.

A rubber composition for a tennis ball includes a base rubber and a high-flatness filler. The high-flatness filler has an average particle diameter D.sub.50 of not less than 1 μm and not greater than 50 μm. A degree of flatness DL is not less than 40 and not greater than 200. An amount of the high-flatness filler per 100 parts by weight of the base rubber is not less than 5 parts by weight and not greater than 100 parts by weight. A ratio (E2/E1) of a tensile elastic modulus E2 in a tensile strain range from 70% to 100% to a tensile elastic modulus E1 in a tensile strain range from 10% to 30%, of a vulcanized rubber obtained by vulcanizing the rubber composition, is not less than 0.60 and less than 1.00. The tennis ball includes a hollow core formed from the rubber composition.

A rubber composition for a tennis ball includes a base rubber and a high-flatness filler. The high-flatness filler has an average particle diameter D.sub.50 of not less than 1 μm and not greater than 50 μm. A degree of flatness DL is not less than 40 and not greater than 200. An amount of the high-flatness filler per 100 parts by weight of the base rubber is not less than 5 parts by weight and not greater than 100 parts by weight. A ratio (E2/E1) of a tensile elastic modulus E2 in a tensile strain range from 70% to 100% to a tensile elastic modulus E1 in a tensile strain range from 10% to 30%, of a vulcanized rubber obtained by vulcanizing the rubber composition, is not less than 0.60 and less than 1.00. The tennis ball includes a hollow core formed from the rubber composition.

An overcap for a container for storing at least one tennis ball, the container extending along a longitudinal axis and having an open end. The overcap includes a body adapted for removably attachment to the open end of the tennis ball container. The body includes a peripheral rim for engaging an outer surface of the container at the open end, and a lip projecting from the peripheral rim toward the longitudinal axis. The peripheral lip extends over a portion of the open end of the tennis ball container. The lip defines a first opening.

Described are balls, in particular a football, and a method for its manufacture. The ball comprises particles of an expanded material. As examples, the particles are connected, at least partially, to each other by radio frequency welding and/or infrared welding. As examples, the ball has a first layer of the particles of the expanded material, wherein the first layer is provided as an outer shell.

A tennis ball including a spherical hollow elastomeric core having a specific gravity of less than 1 and a thickness of at least 4.5 mm, and a textile layer covering the spherical elastomeric hollow core. The spherical hollow core has an initial internal pressure of no greater than 5 psi. The tennis ball has a first tennis ball rebound height when measured at a first time when the tennis ball is unused and a second tennis ball rebound height measured after the tennis ball is exposed to atmospheric pressure for four months following the first time and is unused. The second tennis ball rebound height being at least 96% of the first tennis ball rebound height.