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If we are installing a circular door doorknob, when we opened it, often not knowing left or right rotating doorknob.This is the direction one can tell the door doorknob, its styling is in manpower's grasp, left hand or right hand operation easy, pointing to strong, it can clearly know the direction of rotation of the doorknob, for the convenience of our lives a lot.
Dalian polytechnic University
Dalian, China