A Blu-ray Disc (also called BD) is a high-density optical disc format for the storage of digital media, including high-definition video. The name Blu-ray Disc™ is derived from the blue-violet laser which, because of its short wavelength (405 nm), allows substantially more data to be stored than a comparably sized DVD. A Blu-ray Disc can store approximately 5X as much data as a DVD which uses a red laser with a wavelength of 650 nm. A benchmark for the purpose of calculating duplication speeds, a Blu-ray Disc™ takes about 45 minutes to burn its 25 GB of data at a 2X speed. On average, a single-layer Blu-ray Disc™ can hold a High Definition feature of 135 minutes using MPEG-2, with room for an additional 2 hours of bonus material in standard definition quality. A dual layer disc will extend this number up to 3 hours in HD quality and 9 hours of SD bonus material.