This Mega-Ray Mercury Vapour 275 watt Self Ballasted bulb has been proven to deliver 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. Also because of the very high levels of UVA, stimulates the emotional well being and activity your reptile deserves. This Mega-Ray original design, the only bulb to use a translucent magnesium oxide inner coating in the world, provides the necessary visible light (UVA), UVB and heat for UVB-dependent basking reptiles. For 10 years, it has been shown to have the longest lasting UVB production of any other mercury vapour bulbs available!