Adding rattles to your baits expands the strike zone in stained/muddy water where bass rely less on their vision and more on their hearing and lateral line's ability to detect vibration in the water. Every twitch your rod tip activates Harmony's Double Arm Rattles, creating a clacking sound and vibration underwater that bass will move closer to investigate. The flexible rattle arms allow the rattles to contour to your bait’s shape when swimming or dragging the lure. The soft/flexible arm design causes the internal BB’s to click with even the slightest most subtle movement of your bait. Expandable elastic rubber insert hole easily slips onto all standard hooks and jigs for a secure fit.