4 Colors Wing Sung 3008A Fountain Pen Piston Filling Upgraded Fine Nib Transparent Gold Trim

The piston filling mechanism is easily operated by twisting the knob at the end of the barrel counter-clockwise to extend the piston, submerging the nib in ink, then screwing the knob tight to retract the piston, drawing ink into the pen straight from the bottle—no need for cartridges or a converter! Precision Anti-leaking Rotation Design : operating the piston while ink is in the pen will cause ink to leak out of the pen. You can wist the knob end of the barrel in clockwise to lock it until you hear a "click"