The Sony Optiarc AD-5240S is a DVD burner and reader that was manufactured by Sony Optiarc, a joint venture between Sony Corporation and NEC Corporation. It was designed to be installed in desktop computers and offered high-speed DVD writing and reading capabilities. The AD-5240S supported various DVD formats, including DVD+R, DVD-R, DVD+RW, and DVD-RW. It also had a buffer underrun protection feature to prevent writing errors during high-speed burning. With its reliable performance and compatibility, the Sony Optiarc AD-5240S was a popular choice for users who needed a dependable DVD drive for their computing needs