A racket frame including a first laminate composed of a plurality of first prepregs consisting of fiber reinforced resin and a second prepreg, consisting of fiber reinforced resin, which is layered on the first laminate. The first laminate has a loss factor (=tan .delta.) set to not less than 0.005 nor more than 0.02, when the loss factor is measured at a temperature of 10.degree. C. and a frequency of 10 Hz. The second prepreg has a loss factor (=tan .delta.) set to not less than 0.10 nor more than 0.50, when the loss factor is measured at a temperature of 10.degree. C. and a frequency of 10 Hz.

 
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> Method and device for detecting decompression of tires, and program for judging decompression of tires

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