Pentel's gel is a pigment-based ink which is waterproof and rich in colour. Perfect for creative use or everyday writing, the ink flows smoothly to the last drop. All Pentel gel rollers are acid-free and are therefore suitable for all arts & craft activities. Retractable gel roller for everyday use. Consistent ink flow. Smooth rubber grip. Push button retractable nib. Attractive honeycomb pattern on barrel. 0.7mm tip gives approx. a 0.35mm line width. Single pack containing one Oh Gel pen in black ink.