Dache Aqua Flow Water Brush With A Synthetic Nylon Brush & Refillable Water Chamber. Perfect For Wet On Wet Techniques With Watercolours & For Adding Water To Water Soluble Pencil Drawings With Precision. Simply Unscrew The Brush Nib And Fill The Chamber With Water Using The Screw Convertor & Squeeze Gently On The Push Area For The Water To Wet The Brush And Bleed With Your Chosen Medium. Available In Full Range Of Medium & Large Size Nib. Please See Store For Full Range