An annular sealing element to seal between metal surfaces for use in flanges, joints, packers and the like, located in oil and gas exploration and production equipment. The sealing element has inner and outer metal deformable surfaces joined at ends, defining an interior volume which is entirely filled with a plastic deformable material. The surfaces are arranged such that on compression of the element from the ends, the element will deform in a controlled manner on a cantilever principle. The volume of filler and the interior volume remain substantially equal during compression so that delamination does not occur. Thus the sealing element provides a seal combining the flexibility of elastomer seals with the integrity of a metal to metal seal.