This was bought from a friend who no longer has the manual and I am still not quite sure what it is or what it does.

This is a case for 3.5" HDD that make any 3.5" HDD become external Drive. Here's the product description from Amazon :
The CoolMax HD-360-U2 USB 2.0 3.5" External Hard Drive Enclosure is portable size and excellent quality. The 3.5-inch hard drive aluminum external enclosure is specially designed for high capacity hard drives. And its aluminum material design is great for heat dissipation, so you don't need to worry about your hard drive overheating anymore. The HD-360-U2 Series gives you the freedom to work anywhere, no matter if you're in the office, at home or on the plane. This portable 3.5" HDD external enclosure provides maximum durability, flexibility and portability with various interfaces. Once you download your information to the HD-360-U2 series, you can connect it to any system and gain access to your programs and data files anywhere. With built-in hot swap technology, you can connect and disconnect the drive any time.

Features

• Supports high speed data transfer rates up to 480/400 Mbps
• Fully compatible with 3.5" IDE 133 HDD
• Soft-start for slow turn-on feature prevents high inrush currents when initially powering capacitate loads
• Anti-shock design, protect the hard disk from damage when moving it
• Insulating designed PCB
• Aluminum case transmits the heat quickly
• Powered by a DC 12V-2.0 A transformer