Momiji is Japan's trusted brand when it comes to artist quality brushes. They are made of high quality White Hog Bristle in Nickel Plated Seamless Brass Ferrules.  These strong yet springy brushes can hold a good amount of paint. You can use this for both oil and acrylic paints. These filbert brushes can produce broad strokes or tapering marks. 

Note — Brush sizes are not standard across all manufacturers. You may expect a variation in the sizes of brushes since they may vary considerably depending on the manufacturer.