Advatec Glass Aquarium Heaters feature an accurate Temperature Adjustment Knob, Smart LED Indicator, High Performance Quartz Glass, Precise Digital Control, and have a sleek design that blends into any aquarium. Advatec Glass Aquarium Heaters are trusted for their high performance, reliability, safety features, and ease of use for both Freshwater and Saltwater aquariums! The Smart LED indicator changes color depending on the status of the heater, and features overheat protection with a digital shut off circuit. Enjoy precision Accuracy within +/- 1° F.