This rig is essentially an alternation of the drop-shot rig ( http://www.vingle.net/posts/328575-Best-Bass-Fishing-Rigs-Drop-Shot-Rig), but in a much more compact presentation.
The drop shot wig is great, but can often struggle in heavy cover, and isn't always perfect for the conditions.
Started in Japan, the Jig Rig is an alternation of the drop-shot rig that allows you to fish some different conditions than you might be able to handle with a drop-shot rig, and, it's great for catching bass.
The components of a Jig Rig are as follows:
Dropshot weight attached to a hook by using a split rig.
The benefit of this rig over a traditional drop shot rig or a Texas rig for fishing bass in cover has to do with the location of the weight. A traditional rig has too much leader, and gets caught in cover, and a Texas rig's worm may drop below cover, but still gets caught up when the hook falls in the grass.
The jig rig has both the hook and weight on the same line, so it falls more compactly, and is more sensitive to your motions allowing you to really finesse fish in the cover. This sensitivity makes a big difference, and really will get you some amazing bass.
You can pretty much put whatever lure or plastic you want on the hook, just make sure it matches your conditions.