This is a multi-function writing instrument that combines a 4-color oil-based ballpoint pen (black, red, blue, and green) and a mechanical pencil. The ink uses "Acro Ink," a low-viscosity oil-based ink known for its smooth and dense writing. The ergonomic, easy-to-grip thick shaft and the comfortable silicone rubber grip, characteristic of the Dr. Grip series, reduce strain on the neck, shoulders, and arms during long writing sessions. The ballpoint pen and mechanical pencil have a 0.3mm lead diameter. It has only been used for test writing. Stored at home. Thank you for your understanding and consideration. Thank you for looking.