Abstract: An improvement in the rackets used in tennis and racquetball a round conduit in the frame or head of the racket, which is divided into two chambers by valve elements. A lower chamber containing mercury or other liquid communicates, through the valve elements, to an upper chamber. In use, the liquid is directed, by gravity and centrifugal force, between the two chambers to increase the amount of kinetic energy exerted against a ball, providing for a more powerful swing and improved tennis or racquetball game.