There is 10mm core, triple groove one is watercolor pencils thick shaft. Depending on the amount of adding water, there is a use for triple pencil, crayon, watercolor paint. Axis so thick, it is easy to grasp for a small child who can not have a pencil still firmly. The core is so soft pencil than normal, weak pen pressure, it is recommended to the elderly and children. Based on the ergonomics, round groove around a triangular grip was made to groove pencil series. There is data that write with a force of 70% in comparison with a normal pencil triangular grip. Just hold along the groove around, anyone will be corrected in the correct way to hold.