That is what is known as a "Mendota Rig". Invented and popularized on the waters of Lake Mendota about 45 minutes down the road from me. Bowmandan is correct as to it's use but it's not particularly flexible. In it most primitive form it was a length of coat hanger or copper wire flattened at the ends and drilled to accept a couple of snap swivels. One end connected to your line and the other to a dropper with a lure and/or bait. And yes, the idea was to get back down to 30 - 60 FOW more quickly.
Tackle shop I worked at in the 90s made another version that looked like this:
We couldn't keep 'em on the shelf selling them as fast as we could make 'em. The beads were loose so it would make some noise when you'd shake it, kind of a Perch Talker precursor. They're easy to make with some .029" single strand leader wire, a bullet weight, some beads and a piece of vinyl tubing that kept the weight (Needle Nose Worm weight by Gremlin) locked in place so stuff didn't tangle.
You can also accomplish the same thing (pretty much) with a heavier spoon and a dropper.
