2.5" HDDs are getting more and more popular as their storage capacity is growing. That's why ICY BOX offers a backplane that fits into a single 5.25" unit and is for four 2.5" SATA HDDs. It takes drives up to 15 mm high, for greatest storage capacity.
This IB-2240SK works reliably even with huge amounts of data being transfered making it ideal for RAID systems. While the aluminium casing helps keep the drives cool, two 40 mm fans work reliably and silently.