Applying a mask with a brush helps maintain an even placement of product in a layer that's more consistent than with fingers. Silicone brushes are very easy to clean, making them a better choice than a bristle brush which may retain product and thus become laden with microbes before you use it next. These little brushes have just the right 'give' to them and the handle is a small scoop for picking up mask product with.
These are also perfect for using with Sheet Masks to smooth the mask over the contours of your skin rather than touching the mask with fingers. Use the brush end to smooth over forehead and cheeks, and the smaller scoop end to tuck the sheet mask around nose and to fold the edges of the mask to conform more to your face.