So we cool the solution to about 54 degrees Celsius. And the reason we cool it to that specific temperature is because at that temperature, that is when those DNA primers will begin to bind onto the flanking sequence. Now, because we're going to have so many DNA primers moving about between this region that will keep these two single strands of DNA from forming those bonds and reforming that double stranded helix formation. So in step number two, the solution is cooled to about 54 degrees Celsius and the DNA primers are added. So they're basically floating around. And once we cool our solution to that temperature, those DNA primers are now at an optimal temperature where they can begin binding onto the flanking sequences.