The Propeller Safety Guard has one prime function: SAFETY. The Propeller Safety Guard is an ideal accessory for rescue boats, life boats, water ski boats, dive boats, house boats, pontoon boats, rental boats, children & swimmers in water around boats, etc. Insurance companies love this accessory - so will you. The entire guard and fasteners are electropolished stainless steel. Mounting hardware included.Measuring Tip: Measure distance from under anti-cavitation plate to the bottom of the skeg.