A physical standard for a plastic optical disc physical standard that is 1.2 mm thick and usually 120 mm in diameter, which was officially released in 2006. Blu-ray discs are read with a 405 nm diode blue laser at 36 Mbits/s (1×). Disc capacities are 25 GB for single-layer discs, 50 GB for double-layer discs, and the specification leaves room for more layers in the future.