The blending brush for eyeshadow is one of the most diverse and significant brushes. It is the only necessary tool for eyeshadow application in my humble opinion. The possibilities are endless! Whether you applying a soft sheen onto your eyelid or blending out harsh lines with a dark eyeshadow, the blending brush can work magic. Each makeup brand has their own version, but the MAC 217 is my favorite. The hairs are soft but dense enough to be able to use multiple ways. The actual brush is sleek and easy to store, as well as decently priced! I constantly wash mine and keep it in good condition as well. If you don't own a blending brush and are a frequent user of eyeshadow, you must buy one now! Good luck!