Perfect size for blending darker shadows in the corner of the eye. I found this brushes a little stiff when you first use it which doesn't allow the color to blend out. This was my least favorite brush from the Sigma collection I purchased.

this brush is a staple in any kit. it's soft and fluffy, yet dense -- great for applying a light wash in the crease or on the lid and even better for blending. very comparable to mac's 217.
http://www.sigmabeauty.com/Blending_E25_p/e25.htm