The Doel- Fin Hydrofoil is the original product of its kind. Invented in 1975 by an aeronautical engineer, the Doel-Fin has improved the performance of hundreds of thousands of boats worldwide. The Doel-Fin is the only "true hydrofoil" on the market, designed to provide hydrodynamic lift while minimizing drag. Saves 10%-50% in fuel because of better overall performance! Prevents porpoising and keeps bow lower for better safety. COnstructed of high-impact polymer which is virtually indestructible. Sold with a thirty-day satisfaction guarantee and a lifetime warranty against defect or breakage. Fits all outboards and stern drives from 5 horsepower on up. Model 193 fits virtually every outboard and I/O except the Volvo 280 and 285. Model 193 replaces model 185, and also fits motors below 25 hp.