The Matrix Dark Envy Red Neutralization Mask in a 6.7 fl.oz size is a specialized hair treatment designed specifically for those with dark hair, particularly brunettes or those with color-treated dark hair. This mask is formulated to neutralize red undertones and counteract brassiness in dark hair colors, helping to maintain the richness and depth of the color. It works to deeply nourish and hydrate the hair, leaving it soft, smooth, and more manageable. Additionally, the mask helps to enhance the vibrancy of dark hair colors, ensuring that your hair looks fresh and vibrant. If you're looking to neutralize unwanted red tones in your dark hair and maintain its intensity, the Matrix Dark Envy Red Neutralization Mask could be a great addition to your hair care routine.