The Mega-Ray mercury vapor bulb is our top-of-the-range 70 watt Self Ballasted R80 Narrow Flood Lamp in 120 volt, which has been shown in tests to produce similar amounts of UVB to natural sunlight! Along with adequate heat, the bulb creates a basking spot at the recommended distances in most circumstances (additional lighting and heating should be considered if necessary). It promotes the synthesis of Vitamin D3 and prevents metabolic bone disease, and because of the very high levels of UVA, stimulates the emotional well being and activity.