Abstract: A golf club such as a driver has a two-part sealed cavity. One of the parts extends a limited length along the lower end of the shaft. The other of the parts is of generally flattened teardrop configuration aligned with the shaft axis and located generally vertically in the address position of the club. A pool of mercury partially fills the cavity, but is capable of substantially filling the cavity part located in the club head. The cavity is lined or layered with antifriction material to facilitate flow. A laterally open groove at the top of the flattened teardrop cavity part ensures free flow of mercury.