The Mustad Rolling Diamond Eye Swivel with safety snap is a dependable and easy way to change out lures. The diamond-shaped eye of the swivel guides the line to stay centered, keeping the knot in-line for ideal rotation. To reduce line twist and maximize line integrity under pressure, this swivel features a rolling design. When picking swivel, match the test rating with the rating of your line. Made from brass and coated in Mustad&';s own Black Nickel finish.