| 摘要 |
An needle assembly includes a barrel having a front opening, a rear opening in communication with the front opening, a front blockage formed and an annular rear stop formed on an inner periphery of the barrel to be adjacent to the rear opening. A needle hub is movably received inside the barrel and having a stop ring securely mounted around the needle hub. The needle hub is alternately positioned by the front blockage and the rear stop. A needle is securely mounted at a distal end of the needle hub to be extended out of the barrel when the stop ring is positioned by the front blockage and to be received inside the barrel when the stop ring is positioned by the rear stop. A tube is connected to the needle hub to be in communication with the needle hub.
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