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A rounded cut out at the back of the ruler . Convenient
ruler to get up close to the destop .
We often use a ruler when deliberately with the
pen tip to pinpoint "0"scale , sometimes find not precise, but you can be the front end of the ruler out a small piece , and then rely on the nip up, you can accurately find very accurate , and very convenient . A rounded cat out at the back of the ruler , convenient ruler to get up close to the destop .
East china jiao tong university
Nanchang city, China
East china jiaotong university
nanchang jiangxi, China
Wenyu Hu Junbin Liu Shuai Zhang Yuecen Han