Ace ProFlex F Model OSThe F Model OS gives players a longer fairway driver that has a consistent, overstable finish. It appeals to all skill levels as it still offers a nice bit of glide, standing up to flat when thrown hard. It still offers that reliability and consistency players look for in an overstable disc with a strong finish at the end of its flight. It also has a tendency to skip at the end for some extra movement and utility in shot making.