Abstract: A gasket (10; 40; 50; 70) comprises a sealing member which forms a closed loop extending around a hole. The sealing member is formed from resilient metal and has a transverse cross section which is generally X-shaped and comprises two arms (12, 14) which project inwardly of the hole, and two arms (16, 18) which project outwardly of the hole. The inwardly projecting arms form a first seal around said hole, and the outwardly projecting arms form a second seal around said hole. Each arm extends from a junction (22) with the remainder of the gasket to a tip (24) of the arm which engages one of the bodies. Each arm has its greatest thickness at said junction (22) and its smallest thickness at a point adjacent to or at said tip (24), the arm continuously reducing in thickness between said junction and said point. The gasket can yield from the tips of the arms inwardly as the pressure on the gasket increases.