4 ounce bottle of bright yellow. This yellow goes in easy and heals super bright. When mixed with the green concentrate it allows you to make a wide range of lime greens that will not disappoint. When mixing the green and yellow together in the cap I recommend pouring the consentrate green in first and then filling the rest of the cap with yellow. I usually put 25% green in the cap for light lime green, 50% green for medium lime green and 75% green for a rich dark lime green. Using this method its easy to experiment and mix your own custom tones and easly reproduce them every time.