SWITCH SOLD SEPARATELY. See switch selections for available options. The trim tabs operate independently of one another to provide optimal performance by redirecting water flow at the transom of the boat. Designed to improve the overall performance of a boat. If used properly, Lenco trim tabs will also improve the fuel efficiency of your boat. Lenco actuators are electromechanical, they provide an immediate response at the touch of a button. The actuators mount at the trailing edge of the blades requiring less transom height than standard mount tabs. Height needed for actuator: 11" Heavier boats or boats 25' and up that run at more moderate speeds should be fitted with 12" tabs with increased width. Faster boats (50mph+) may be better suited to longer racing tabs.