-WHAT IS IT-
This type of brushes are called are pentel aquash waterbrush. They can have a variety of shapes, sizes and colors and they are very practical because,you can put water inside them, that way you wont need to be dipping the brush in water every time you need to get a softer or stronger color.
-HOW TO USE IT-
First we have to separate the brush carefully making sure that it doesnt break as we can see in the picture below:
Then you take the water container (the part of the brush wich is at the rigth) and you fill it up with water.
After we did this we have to close the brush again and take some watercolors and use it as a normal brush, with the difference that everytime you press it a bit of water will come out and ix with the color that you are using.