48 in.. 10,000k high intensity lamp with strong emissions in the blue spectrum simulating deeper ocean environments. Ideal for all marine aquariums, reef tanks, and fresh water aquariums where a deep water effect is desired. Emission spectrum strong in the blue and red regions which supports the photobiological processes of marine algae and fresh-water plants. Promotes the growth of zooxanthellae algae, essential for the growth and well being of all photosynthetic corals and invertebrates. Long lasting: Effective for up to 10,000 hours. Info from ZooMed