This is a fantastic solution to adding length and volume with different colors. I love this for my clients who want more density, but don't want to commit to permanent installs.
 
The Layered HALO® is our most popular extension. Uniquely designed and unlike any other product available, it has 2-3 built-in, gradual layers, providing a seamless blend with natural hair. With 30% more grams than The Original HALO®, The Layered HALO® delivers maximum volume for dense or thick hair. -Halo