Red sign / Pen / Pen

“Red sign” tells you when you have to replace your ink. “Red sign” make a use of two colors to inform you of when you should replace ink. Unlike widely-used pens, we put a red ink at the end of existing ink inside the pen. Therefore, people might find a red ink on a piece of paper when they should replace their ink. Even though you cannot write down anything with that pen, You even can see the ink is not used up yet unless red ink comes out. You even can get rid of red ink written down on the paper using the eraser of pen which is located at the end of pen.