KingWin Multi-Bay Internal Rack with 4 Drives for 3 Bay Space SATA Mobile Rack, KF-4001-BK
A multi-bay SATA internal hot swap enclosure that takes 4 hard drives with only 3 bay slots.  It also supports RAID, instand HDD installation, and hot swap ability.  This space saving multi-bay enclosure is easy to use, and simple to install.