Hourglass Domed Shadow No. 9 Brush is probably the best synthetic eye shadow brush I own. While normally I prefer sable hair for the delicate eye area and soft eye shadow textures, there is something to be said for soft Talkon bristles. I'm already familiar with the high quality of Hourglass makeup brushes- the metallic handles are pretty and sturdy, the heads are carefully assembled and shaped, and they keep their shapes beautifully through constant use and abuse.
Hourglass Domed Shadow No. 9 works well for precised contouring, smudging, crease-cutting and even for highlighting the tear duct. The brush is very soft so there'll never be any poking by an errant hair; it's also tightly packed so it grabs a lot of product and spreads it evenly. Do keep in mind that when dealing with very dark and/or intensely pigmented eye shadows you only need a light dip in the pan, but that's always true, right? In the case of Hourglass No. 9 the brush will deposit quite a bit of the product in a very concentrated area, but it's also quite good at blending and diffusing it.
For comparison I used two classic domed brushes: the discontinued Paula Dorf Smokie Lid (newer rounder version) and Sephora Professional (formerly Platinum) Natural Dome Smudge Brush #13. Both are more of a smudge brush while Hourglass No. 9 has longer hair that makes it suitable for blending the crease.
Bottom Line: excellent.
Hourglass Domed Shadow No. 9 Brush ($28) is available at Barneys and Bergdorf Goodman.