Refillable Pencil Design: Each refillable watercolour pen comes with a built-in water tank that allows you to adjust the flow of water with light pressure for easy control. Transparent barrel makes it easy to check the amount of water in real time, preventing wastage and ensuring that the water is always wet when painting. High Quality Nylon Brush Tip: These replaceable water reservoir brushes are made with flexible and durable nylon tips that retain their shape even after long periods of use. Suitable for outlining details and applying colours to large areas, providing you with precise and smooth lines. Ideal for sketching, swooshing, calligraphy and other painting styles. Easy To Use:Leak-proof construction ensures a clean and tidy drawing process. Simply open the barrel clockwise, fill with water or diluted ink and tighten the barrel counterclockwise. The pen is then squeezed gently to dispense water, making it easy to use. It is recommended to empty and clean the pen in time after use to avoid residue and affect the effect of the next use. Compact and Portable :Each watercolour brush pen comes with a protective cap, lightweight and easy to carry, designed for creating on the go. Suitable for outdoor sketching, doodling on the go and everyday carry, can be easily put into the pen bag or backpack, ideal for sketching activities and travelling painting Widely Compatible:This refillable water brush pen is compatible with a wide range of painting mediums, including watercolour paints, water-soluble colour pencils, dye inks and more. Suitable for watercolour calligraphy, colour mixing, handbook creation and DIY greeting cards. Suitable for artwork and craft projects, ideal for students, hobbyists and illustrators.