Optical disks are the ideal solution for long-term and secure storage of your important files - ideal for your precious photos, videos and documents that you want to keep forever. Not only are they dust and water resistant, but they can also withstand wide fluctuations in temperature and humidity. The double/dual recording layer has been made possible by creating a new substrate layer that sits between each recording layer. This allows the laser beam to record on both layers. When the first layer has been written, the laser writes to the second layer. 8.5GB capacity on a single disk!