The Exo Terra Turtle UVB Bulb provides all the necessary light conditions for aquatic turtles. The Turtle UVB Bulb's balanced ultraviolet and visual light spectrum prevents shell softening and deformation while, adds to the physiological well-being and brings out the beauty of aquatic turtles. The bulb will contribute to the overall health of your turtles by providing the necessary UVB rays for optimal calcium metabolism while the UVA rays will contribute to the turtle's welfare.