This is a flat top buffer brush with a small diameter brush head. The brush head is about an inch in diameter so is smaller than most buffer brushes (I've never come across one so small). The bristles are natural hair, and is packed densely so the brush is firm.
Overall I would say that this is a unique brush as the small size makes it useful for buffing in small areas for precise application and blending. It could be used for blush like its name suggests or also for powder and foundation, which is how I use it more often. However the bristles are not the softest and can feel scratchy and coarse. I would not use this on someone with sensitive skin as it would definitely irritate. I have washed it several times and unfortunately the brush hairs have not softened so it's obviously the nature of the brush hairs.
I am a brush collector so had to have this for my collection and would recommend this to other make-up artists but not to anyone else due to the roughness of the bristles. Other flat top buffers such as the Everyday Minerals one, the Stila bronzer brush or Coastal Scents synthetic flat top buffer are much nicer to use (although bigger in size).