Swivels are used to prevent your line from twisting. If you’re casting a spoon a swivel is a must use piece of tackle. If your bottom fishing with a weight you must use a swivel. When trolling you must use a swivel. Remember free lining live Bait a swivel is not necessary, it will only weigh down your bait and prevent it from swimming naturally. Swivels range in size and strength. Use accordingly to your gear. Here are some swivels you should have in your tackle box.