The Pentel Aquash Water Brush 3 Pack Fine, Medium & Broad contains 3 brushes that have nylon tips and each have a 10ml water reservior. These handy brushes are ideal for travelling artists and can be used whenever and wherever you need them. To use the Pentel Aquash brushes simply fill the container with water and gently squeeze the sides of the brush to allow the water to drip into the brush. You then have a permanently wet brush whenever you need it. Idea for use with watercolours, pen & ink, watercolour pencils, water-based marker pens and watercolour inks.