The SLT reacts instantly to boat speed and water pressure by adding trim when it’s needed. At slower speeds, when the boat is trying to get on plane, the actuators hold the trim tabs down, which lifts the stern and simultaneously puts the boat at planing attitude. On plane, and as the boat’s speed increases, water pressure pushes the tabs up. You will enjoy a smoother ride while the SLT does all the work. Ideal for boats longer than 17', the actuators have are pre-set with a 90lb. spring that responds to both boat speed and water pressure to provide trim precisely as needed to improve your hole shot, reduce engine laboring, improve fuel efficiency and eliminate porpoising. get on plane faster improve your fuel efficiency reduce pounding and engine laboring. Ideal for boats longer than 17', the actuators have are pre-set with a 90lb. spring that responds to both boat speed and water pressure to provide trim precisely as needed to improve your hole shot, reduce engine laboring, improve fuel efficiency and eliminate porpoising. eliminate porpoising and chine walking durable spring-action system Fit type: Universal Fit MODEL NO - SLT10