A swivel is a small metal connector joining the main line with a leader or rig. Its rotating design prevents the line from twisting when the lure or leader spins.
It is useful when spinning, jigging, bottom fishing or using lures that rotate. Also important when using leaders that can twist the line or when rigs must be changed often.
Consider strength and load capacity — the swivel must withstand the force of the targeted fish. Use small swivels for light lures and stronger ones for heavy rigs or big fish.