The Hammer Four Density (4D) Core consists of four individual components, top flare ring, top cap, mid body and lower cap. All four-core parts are of different densities. The 4D-core body is placed in an offset position in the relation to the centerline of the ball. This is the ball's drive mechanism. The Hammer HPT, for Hammer Particle Technology, is the latest development in Active cover materials. HPT is the production process where millions of tiny material particles are interspersed throughout the urethanes used in producing the ball's cover. These material particles create the ball's grab on the lane resulting in increased frictin, causing more hook than balls with today's reactive or conventional urethane covers. The HPT cover creates a high rate of ball friction. Friction, combined with ball momentum, initiates the hook action while keeping the ball's energy in check for devastating pin carry. The 4D core compliments the HPT cover, giving the ball drive and revs. What are the results? It's coast to coast hook, baby! Turning the Corner just took on a whole new meaning.