Blu-ray Disc recordable
Blu-ray Disc recordable refers to two optical disc formats that can be recorded with an optical disc recorder. BD-R discs can be written to once, whereas BD-RE can be erased and re-recorded multiple times. As of January 2008, BD-R/RE drives up to 6x speed are available from retailers for about US$450,and 4x single-layer BD-R discs, with a capacity of 25 GB, can be found for around US$12. The theoretical maximum speed for Blu-ray Discs is about 12x as the speed of rotation (10,000 rpm) causes too much wobble for the discs to be read properly, similar to the 20x and 52x respective maximum speeds of DVDs and CDs.Since September 2007, BD-RE was also available in the smaller 8 cm Mini Blu-ray Disc diameter size.