One of the only T5 lamps with 100% True Actinic 03 Phosphors T5 diameter high output fluorescent lamp. Actinic 03 that peaks between 420 and 430 nanometers. Simulates the blue hue of deeper water. Assists in the growth of Coralline Algae. Perfect for supplementing daylight lamps in saltwater tanks. A great quality lamp at a great price