ProLiant servers are separated into four main product lines - ML, DL, BL, SY, and Apollo - which generally denote form factor. The ProLiant ML line comprises tower-based servers (convertible to rack mount) with capacity for internal expansion of disks and interconnects, while the DL line comprises general purpose rack mount servers. The BL line comprises blade servers which fit within the HP BladeSystem, the SY comprises the Synergy Blades, and the Apollo line comprises servers for scale out and High Performance Computing environments. The MicroServer product line addresses small and home businesses.