The SI Swivel system is a convenient upgrade that increases the functionality of your board rack. With three locking positions, the SI Swivel allows safe loading and unloading of your boards without damaging your boating equipment, and anti-vibration rubber dampener protects boards while your boat is under way. Easy-pull manual locking pin. Includes adaptor plate for mounting SI Swivel to universal clamp. Brushed anodized finish is saltwater-friendly.