新颖性：The duster (1) has an air supply pipe (2) whose outer side is provided with an air supply hole (2a). Closure covers (6,7) are arranged for covering both ends of the air supply pipe and are fixed to tension fixing device (4). A nipple unit (8) is assembled in one side of one closure cover (6). The tension fixing device is provided with a cut-out portion (4a).;
适用于：B ........
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