Zilla 11521 36-Inch Desert 50 UVB T5 Fluorescent Bulb, 21-Watt This bulb is for a Zilla 36 inch Fixture (actually its only 34 inches long) Ideal for desert dwelling reptiles Delivers UVB light levels essential for desert reptile health Full-spectrum illumination accents subtle pet colors Styles to fit fluorescent, incandescent light fixtures Bring a ray of desert sunshine to arid reptile habitats