This product was developed in collaboration with designer Yuji Baba. This eraser has five erasing widths, allowing you to erase "one line" without erasing the lines above or below it, depending on the width of the notebook's ruled lines. Erasing widths: 6mm width - for A-ruled notebooks, 5mm width - for B-ruled notebooks, 4mm width - for C-ruled and 5mm grid notebooks, 3mm width - for planners and small writing, corners - for fine details. The number indicating the erasing width will not disappear even if the eraser is worn out. Made with environmentally friendly non-phthalate plasticizers. **Reseller Disclaimer: Kokuyo items cannot be sold on Amazon, eBay, or Walmart.com.**