And when this transformation takes place, that once again causes a color change. So we see the principle that we use is this color change reaction. It's the color change reaction that signifies the presence of either that antibody or that antigen in our sample. So the well is washed to remove anything that is not bound, and the substrate is added to react with the enzyme producing that product that gives off that color. And just like in the case of indirect Eliza, in sandwich Eliza, the darker that color is, the higher the concentration of that antigen. And the lighter the color is, the smaller the concentration of our antigen.