The ReptiSun UVB Lamp contains the highest amounts of both UVB and UVA wavelengths (according to an independent laboratory spectral analysis.) UVB wavelengths aids in preventing and reversing Metabolic Bone Disease in green iguanas as well as other species of pet lizards. Strengthens and improves shell growth on all captive turtles and tortoises. UVA wavelengths increase appetite, physical activity, and help to induce reproductive behaviors as well as being beneficial to the psychological well-being of captive reptiles and amphibians. Safer than adding powdered or liquid synthetic D3 supplements, as the UVB wavelength allows all reptiles the ability to regulate their own Vitamin D3 levels by endogenous synthesis as they would in nature! Eliminates the risk of vitamin D3 overdose (highly toxic) from synthetic sources. The lamps wavelength penetrates a full 10-12" from the bulb's surface. Pure quartz glass sleeves. The bulb's UVA/UVB wavelength remains effective for 1 to 1-1/2 years.