I was looking for a brush to pack on eyeshadow as a base color. This does so evenly and easily. An unexpected (to me, at least) alternative it works for as well is to precisely place eyeshadow into the contour of the eyelid, which is very useful when attempting a smoky eye. Thanks for an awesome brush :)
As always, mac makes great brushes. I use this one to apply glittery or intensely pigmented colors (like the electric line) to push them in the center of my eyelid before gently Blending out. This brush helps eliminate fall out.