A broad spectrum daylight lamp. The spectrum is ideal for plant's photosynthesis & the UVA (ultraviolet A) light contributes to reptiles' physiological well-being. Another important factor is the heat emitted by this bulb to increase the all over ambient temperature in the terrarium. Can be combined with Night Glo or Heat Glo for a 24-hour cycle.T10 available in 15watt, 25watt & 40watt A19 available in 60watt & 100watt A21 available in 100watt & 150watt