Federal Hydra-Shok Deep, 9MM, 135Gr, Hollow Point, 20 Round Box P9HSD1 Federal Premium(R) Hydra-Shok(R) has proven itself for self-defense since 1989. Hydra-Shok Deep(TM) builds off the time-tested platform with design improvements that better meet modern performance measurements. The bullet features a more robust center post and a core design that penetrate to optimal depths through the barriers most commonly encountered in self-defense situations.