The Pentel Aquash Water Brush has a synthetic nylon brush with refillable water chamber making it the perfect tool for any watercolour painter. The Broad brush is ideal for areas of dense colour and large washes. Simply unscrew the barrell and fill the chamber with water, then squeeze gently for the water to wet the brush and blend with your chosen art medium. The Aquash brushes are ideal for wet on wet techniques with watercolours and perfect for use on the move where there is no water supply. These Aquash Water Brushes will hold 10ml of water. You can also wet, mix and apply watercolours with this excellent brush!