The New and improved range of UVB linear tubes from Exo Terra replaces the popular Repti Glo range. Replacing the ET Repti Glo 5.0 T8 tubes the new ET Reptile UVB 100 T8 tubes do away with the percentage terminology of linear tubes and instead focuses on the average UVB output, based on a basking distance of 10cm from the lamp. No longer should you have to rely on the 5.0 principle which only vaguely indicates the UVB output of the lamp ranging between 280 - 320nm. The 100 terminology focusing on the 290 - 310nm wave length which is the range responsible for vitamin D3 synthesis. Combined with Exo Terra's new UVB lighting app the right lighting requirement is no longer an educated guess but can actually put the onus on the keeper allowing for better accuracy between keeper and retailer. All of the new ET lamps have been designed for maximum vitamin D3 photosynthesis by concentrating the UVB output near the 294nm wavelength (the wave length responsible for peak D3 production).