The MB974SP-B at first glance looks like it will take up all four 5.25-inch drive bays, but it actually fits into three, but gives you storage room for 4 SATA hard drives. This is good for 2 reasons, one many cases only have three 5.25-inch drive bays, two if a case has four open 5.25-inch drive bays the MB974SP-B only takes up three so you have room for an optical drive.
On the front of the device you have four drive bays that support 3.5-inch SATA drives, even SATA 6GB/s drives up to 3TB. On the left side of the device you have power and activity LED’s for each drive, an eSATA port, USB 2.0 port, and fan speed control. The power and activity LED’s are actually power buttons for each drive.
Opening each drive bay up is very easy. There is a button on the inside of the latch that you press in then just pull the door towards you to open the each bay. With all of the drive bays open you can see that while the front bezels are made of plastic the internals and closing latch are made of metal.
If we take a look inside you can see how the MB974SP-B works, there is a PCB which acts as a SATA backplane with the SATA power and data connections so when you slide your drives in they connect right in. On the side of the device you have mounting holes which should line up perfectly inside of your case.
Looking at the back of the device things are a little busy. Starting on the left side you have 2 SATA power connectors. It is nice to see SATA power connectors, not molex connectors here. So many devices like this use molex connectors and its annoying to have to get out a molex connector for your modular power supply just for a device like this. In the center is an 80mm cooling fan that should keep your drives nice and cool. On the far right side you have 4 SATA data connections, one for each drive of course. There is also a SATA cable for the eSATA connection and an internal USB 2.0 connector, which you connect to the headers on your motherboard. If you get lost with all of these connections there is a guide on top of the device.