The Pentel Aquash Water Brush 3 Pack Fine, Medium & Flat contains 3 handy brushes that feature durable nylon bristles and are perfect for watercolour work. Each brush has a 10ml water reservoir that feeds water from the tank into the bristles which is ideal when painting whilst travelling or outdoors. To use Pentel Aquash brushes, fill the reservoir with water up to the fill line and re-attach the brush. Then, simply squeeze the sides of the water tank to force the water onto the bristles and down onto your paper. Great for designers, artists on the go, painters, crafters and artists who use watercolour pencil.