When the first protruding portions 141 a receive vibration, the through holes 144 may provide space for {HEAD ~ the deforming} of the first protruding portions 141 a in order to buffer the vibration received by the first protruding portions 141 a. In this embodiment, {TAIL ~ the number} of the first protruding portions 141 a and the through holes 144 is two, but it should not be construed as a limitation to the disclosure 
When the first protruding portions 141 a receive vibration , the through holes 144 may provide space for { HEAD ~ the deforming } of the first protruding portions 141 a in order to buffer the vibration received by the first protruding portions 141 a. In this embodiment , { TAIL ~ the number } of the first protruding portions 141 a and the through holes 144 is two , but it should not be construed as a limitation to the disclosure
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