4 ounce bottle of blue concentrate. This blue goes in easy and heals super rich and solid. When mixed with the El Blanco it allows you to make a wide range of blues that will not disappoint. When mixing the blue and white together in the cap I recommend pouring the consentrate blue in first and then filling the rest of the cap with white. I usually put 10% blue in the cap for light blue, 25% blue for medium blue and 50% blue for a rich blue tone. It also looks amazing when used uncut for a very dark blue. Using this method its easy to experiment and mix your own custom tones and easly reproduce them every time.