A tennis ball may include 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 hollow core

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.

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.

A filling device may be used to fill a ball or other inflatable item from a water source such as a hose. A filling device may include an adapter having a cylindrical body with a hollow threaded interior, one closed end and one open end. A filling coupler is coupled to the one closed end of the cylindrical body. The one closed end of the cylindrical body has an opening formed therethrough and the filling coupler is coupled to the one closed end covering the opening. The filling coupler has a hollow threaded interior in fluid communication with the opening. A tip may be removably coupled to the filling coupler. The tip may be a ball inflation needle, a water balloon filling tip or the like.

The disclosure relates to a sealed pressure container, which solves the problem in the prior art that a pump is required for providing air pressure in the container. The conventional product is inconvenient for carrying and is expensive. The sealed pressure container includes a body and a winding member. The body has an open end and a flexible portion, the flexible portion is at least one part of the body at one side where the open end is formed. The flexible portion can be wound around the winding member from the open end to provide air pressure in the body by compressing the air inside the body. Thus, without using a pump, tennis balls can be prevented from releasing pressure by keeping in the low-cost sealed pressure container. The sealed pressure container is convenient for carrying and operating and has reduced manufacture cost.

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.850TGA.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 rubber composition for a hollow ball includes a base rubber, an inorganic filler composed of a large number of flat particles, and a carbon-based filler. As to the carbon-based filler, a degree of flatness DLc obtained by dividing an average particle diameter D.sub.50.sup.c (m) by an average thickness Tc (m) is not less than 50. A weight ratio Mc/Mi is not less than 0.01 and not greater than 1.00. The rubber composition is obtained by a production method including: a first step of mixing the base rubber and the carbon-based filler to obtain a master batch; and a second step of adding the large number of flat particles that form the inorganic filler, to the master batch to orient the large number of flat particles. The hollow ball 2 includes a core 4 formed from the rubber composition.

A rubber composition for a hollow ball includes a base rubber, an inorganic filler composed of a large number of flat particles, and a carbon-based filler. As to the carbon-based filler, a degree of flatness DLc obtained by dividing an average particle diameter D.sub.50.sup.c (m) by an average thickness Tc (m) is not less than 50. A weight ratio Mc/Mi is not less than 0.01 and not greater than 1.00. The rubber composition is obtained by a production method including: a first step of mixing the base rubber and the carbon-based filler to obtain a master batch; and a second step of adding the large number of flat particles that form the inorganic filler, to the master batch to orient the large number of flat particles. The hollow ball 2 includes a core 4 formed from the rubber composition.

An elastic spheroid structure includes a hollow elastic spheroid body having an elastic spheroid shell, a receiving space formed inside the elastic spheroid shell, and a through opening passing through the elastic spheroid shell and being in air communication with the receiving space. The through opening has a first predetermined shape, the through opening has a first middle portion and a plurality of first extending portions extended outwardly from the first middle portion, and the first predetermined shape of the through opening is formed by connecting the first middle portion and the first extending portions. The elastic spheroid structure further includes a solid elastic cover body disposed inside the through opening of the hollow elastic spheroid body and a connection layer disposed inside the through opening and connected between the elastic spheroid shell and the solid elastic cover body.

An elastic spheroid structure includes a hollow elastic spheroid body having an elastic spheroid shell, a receiving space formed inside the elastic spheroid shell, and a through opening passing through the elastic spheroid shell and being in air communication with the receiving space. The through opening has a first predetermined shape, the through opening has a first middle portion and a plurality of first extending portions extended outwardly from the first middle portion, and the first predetermined shape of the through opening is formed by connecting the first middle portion and the first extending portions. The elastic spheroid structure further includes a solid elastic cover body disposed inside the through opening of the hollow elastic spheroid body and a connection layer disposed inside the through opening and connected between the elastic spheroid shell and the solid elastic cover body.