It's the Fillimilli 855 brush.

It has the advantages of a fan brush, and its small size makes it convenient to carry around. The brush length is said to be 13cm. Fillimilli products really have great brushes. In particular, this product doesn't clump when applying shading, and it makes it easy to create contouring effects. It even comes with separate brush cleansing wipes. For those who use it daily, I think it would be great to be able to wipe it clean with the tissues! Also, it is recommended to store it in a dry place. I highly recommend it!