O.S. developed the Surpass Series of 4-stroke engines for discerning fliers who demand more power. The OS FS-120S-E Surpass Engine performs flawlessly for the most demanding applications. It is able to swing larger props and supply more usable horsepower and provide the best performance for your plane, regardless of scale or flying style. All Surpass engines feature a helix gear-driven camshaft on the front end and dependable updraft carburettor in the back.