The Litepanels 1/2 CTO 1x1' Gel is designed especially for the Litepanels 1x1 LED 5600°K fixture. A full CTO gel will make the light mimic tungsten light. Sometimes, you may want the light to be somewhat "cooler" than tungsten, with more blue in it, so the gels are also available in fractions--this 1/2 CTO gel changes the color of the 1x1 5600°K fixture to 3800°K--warmer than the unfiltered light. The 1x1' gel is designed to slide into the front of the fixture. Full, 1/4, and 1/8 CTO gels are available separately.