Cagi Sonic Fish Attractor is one of the most popular attractors used for trolling in the United States. The device consists of a propeller placed inside a plastic tube, which spins to produce an effect that makes predators think of the lure as an easy catch. Place the attractor approximately 50 cm in front of your lure. Most effective when trolled at 1–3 miles per hour (1.5–5 km/h).