The DS Shake Pen presents an innovative shaking technique through which the ink cartridge can be released and retracted through a little forward or backward shake of the wrist. The counterweight spring inclines to the nib as driven by inertia, thus pushing the connector forward and the nib out. Meanwhile, the rear clip moves from the back slot in the barrel to the front slot, fixing the elastic tip spring to prevent the cartridge from being retracted when writing.