The split rings are an auxiliary element that prevents the tackle from tangling with the fishing line. The main advantage of the rings is their compactness.
These rings are needed mainly for fishing spinning rods: for attaching artificial lures to the fishing line or for attaching leads with a sinker. The rings were most popular in jig, twitching and trolling techniques.
The use of a swivel prevents the line from twisting, provides free rotation without much effort, increases reliability when fishing with strong currents and helps to quickly change equipment elements.
Swivels are necessary for spinners, devons, catching with a bombard. Moreover, for bombards and devons, it is advisable to use double, or better triple swivels.
The lock snaps is used to quickly change the elements of the rig, and also takes the load on the entire fishing structure. Typically, a lock snaps is used between a bait (eg a twister) and a load. If feeder fishing is performed, then the lock snaps is used to attach the feeder.