source: www.vogue.com.tw/beauty/beautynews/content-12067.html
There's a little write up on them, but in Chinese. Going by the google translation they are for wet and dry use; the big one is for the face (foundation, blush etc), the middle one for smudging e/s or for small areas like around the nose and the smallest one is for brows, lining lips and other small details.