this brush is marketed to apply colour to the contour of the outer eye socket and to blend. for a long LONG time, i've been eyeing this but never actually bought it because it looked like it wasn't tightly packed enough to really do anything, but was always curious.
this brush is made from natural hair and is very soft, a tiny bit loose (as in not dense), and has a shape that is a little flat, so when you wash or wet it and flatten it back into its original shape, if you look at it from top you will see it taper into a flat edge if that makes sense.
what this does, is apply colour EXACTLY in the contour of the outer socket, but applies it so lightly so that you can build it and blend it. i use this to add black into my outer eye socket as a finishing touch and then blend it. you can also turn the brush horizontally, to then blend it 'out' towards your temples for a more cat-eye shape. it works a charm and i never want to be without this now.
on to the quality of the brush, i have spot-cleaned this brush about 6 times since owning it, and the black eyeshadow hasn't really stained the bristles a lot. maybe in the densest area of the brush it looks a bit grey. i think deep cleaning will solve this problem if that's an issue for you. also, the brush has retained its original quality and performance after each spot-clean. an important tip is to flatten the brush back into its original shape while its still damp/wet, so it actually dries back into its original shape, otherwise it will eventually splay. lastly, this has only shed ONCE, a few hairs.
on a sidenote; i have also seen this compared to the MAC 217, which i don't own by the way.
i think this is an excellent brush and highly recommend it, it's changed the way i apply my make-up, saves me time, and really gives my eye make-up a more high quality and blended look!