The Matrix Dark Envy Neutralizing Dyes Mask is specifically formulated for dark brunettes to neutralize red undertones and maintain the richness of their hair color. This mask helps to enhance the depth and intensity of dark brown shades while neutralizing any unwanted red or orange tones that may develop over time. It typically comes in a pack of two 16.9 fl.oz bottles, providing ample product for multiple uses. By using this mask regularly, brunettes can achieve a more balanced and vibrant hair color while keeping it looking fresh and rich.