This Piston Filler Waterbrush was bought from Amazon. The pack came with two identical waterbrush. The brand is Wen Lian, that's if I translate the Chinese words correctly.
The round tip of this waterbrush is quite broad. I'm not sure what the bristles are made of, but it doesn't look synthetic.
The body is made of plastic while the cap is metal. The cap is not particularly tight and doesn't close with a 'click' sound. The construction doesn't feel very sturdy.
It uses a piston to fill and release water. You have to dip it into a container of water or ink and turn the piston to suck the water in. This means you can't fill the waterbrush direct from the tap.
Unlike the squeeze-type waterbrush, the water doesn't flow continuously. You need to turn the piston to push the water out, or load the bristle with water. This is much like using a normal brush, when the water runs out, the brush becomes dry (relatively). To use it again, you have to push more water out. Having more control over the water flow means there are less surprises from random release of water.
It's easier to achieve a flat wash with this waterbrush, relatively speaking. You just create a watercolour mix, then brush across the paper as usual, just like you would with the normal brush. With the squeeze-type waterbrush, the water is always flowing so you're always creating a gradated wash.
The downside is the size of the reservoir. It's not very large and water can be used up quite quickly. To refill it outdoors, you need to have water in some sort of container. Maybe that's why the seller sells it two in a pack.
The other downside is the waterbrush seems to lose bristles easily. A few come off the tip while I was refilling water and painting. I'll update more on this in the future.
3.5 out of 5 stars.
Search Jackson's Art Supplies (UK) also.