The bulb simulates the natural daytime photo-environment of a desert or tropical habitat while providing a heat source needed for a healthy reptile environment. Photons from the daylight bulb pass through the glass heating the opposing surface allowing the reptile to bask in its warmth. The bulb is made from glass containing rare earth neodymium phosphors to produce a brighter, whiter light. This full-spectrum lamp emits energy across all visible wavelengths from 400nm to 700nm and UVA rays from 315nm to 400nm. *For UVB output, use Zilla Desert 50 or Tropical 25 UVB Fluorescent Bulbs This Product/Package Measures: 2.50 in. L x2.50 in W x5.25 in D br/>Sold as 1 Piece(s)