The purpose of the is to keep your hooks from tangling up with your line. 

The consist of a swivel on top, brass tubing in the middle and a lock snap on the bottom. The will withstand normal abuse such as rocks and roads that you might come in contact with while jigging a spoon.

To connect the first tie the swivel to your line then connect your spoon to the snap. The snap keeps the spoon hook from crossing the line. Therefore the   keeps your line and spoon separated  maintaining natural motion and eliminating most spoon fouled lines.