Internal IB-172SK-B designs to fit in a standard 5.25" CD-ROM bay with one of 3.5" HDD and one of 2.5" HDD housing slots. The tray-less design and hotswap function increases data mobility and the convenience of data exchange among HDD. IB-172SK-B also gives an advantage of the full usage from space limitation to offer an ideal storage to workstations, DIY groups and the individuals.