The TPE-111GI is a Gigabit speed PoE device that allows you to take a standard Ethernet connection and "inject" power to the line. This is a handy little device if you do not need something like the TPE-S44. In some cases you may only need one PoE line; with the TPE-111GI you can run this straight from your regular switch and not have to foot the extra cost for a full PoE switch.
The design is quite simple and really consists of not much more than a "brick" that you would plug into the wall. On one side you would have the non power Ethernet connection and on the other would be the powered side.