Features Using imported ink, high permeability A free pen tip is provided to extend the service life and increase the added value of the product. Working life: The marker ink weighs about 5g, and 1g can draw about 55m-61m. One marker pen can draw about 277m-309m. After testing with PH=3 and PH=12 acid and alkali solutions, no decoloration or fading occurred, and it is also waterproof. The ink is brighter and the marked number can be clearly identified from a distance