Bait Clips are used to help streamline your rig when casting. This helps to give you extra distance which is often quite crucial to get into the next gutter or channel where the bigger fish are.
You just clip your baited hook onto the bait clip and this holds your bait close in to your rig while casting. It stops your bait from flapping and spinning around in the air causing resistance. Your baited hook automatically releases on impact with the water allowing your bait to present itself perfectly once in the water.