Sunday Riley's Eye Definer is a small domed brush that does a great job placing color, defining the crease or smudging along the lash line. It's not quite as pointed as a real pencil brush (not pictured here, but in comparison to MAC 219 Sunday Riley Eye Definer brush is rounder and about 2mm shorter. It's also less firm and its hair is softer). The hair has some give and movement, but it's still good for detail and precision work. The soft hair feels nice even on the most sensitive areas of the lid and I use it in rotation with the other similar brushes you see here, especially my favorites: By Terry Dome 3 and the Hakuhodo ones (I already reviewed B533, G5520 is coming soon).
Bottom Line: Great.
Sunday Riley Eye Definer Brush ($28) is available at Bergdorf Goodman, Barneys, and Dermstore.com. The brush I have was part of a gift bag at a Bergdorf press event.