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When I use the thumb tack,Sometimes not enough length of the thumb tack.At this time,I hope that the pushpin can
have a longer.Sometimes,Pushpin in the face of soft or hard object when there are many shortcomings,Too soft
objects, the pushpin will fall,Too hard objects, the pushpin will not be easy to enter.At this time,I am inspired
by the screw,Pushpin in the nail tip be made a screw.Pushpin plastic handle into two parts,Plastic was removed
half of the Pushpin become longer pushpin,Otherwise,the general pushpin.
Luo Shijian;Ying Fangtian
Ji Qiangqiang;Dong Wei;Li Xue;Hang Tiangshu