The Juwel High-Lite tubes in the coloure Day creates a cool and bright light with a colour temperature of 9000 Kelvin. It enhances natural colours and plant growth. For Freshwater it is recommended to use a combination of the tubes: Day + Nature or Day + Colour.Juwel High-Lite refers to the new light technology by Juwel Aquarium. It combines the existing tube lengths of the T8 with the new bright T5 technology.the following lengths of the Juwel High-Lite tube Day are available:-24 W - 438 mm-28 W - 590 mm-35 W - 742 mm-45 W - 895 mm-54 W - 1047 mm-54 W - 1200 mmPlease note: it is important to know, these tubes are only fit in the new Juwel Aquarium covers with High-Lite technology. These tubes have special lenght and will therefore not fit other lamps, also if the wattage is the same e.g normal T5 tube 24 W = 549 mm, Juwel High-Lite T5 tube 24 W = 438 mm.