Aleratec Blu-ray 4x BD-R 25GB disc is the next-generation optical disc format that was developed to enable recording and playback of high-definition video (HD), as well as storing large amounts of data. A single-layer Blu-ray Disc can hold 25GB, which can be used to record over 2 hours of HDTV or 23 hours of standard definition video as well as PC data storage.