Capsule containing a substance for the preparation of a potable beverage by extracting and/or dissolving the substance by means of supplying a fluid under pressure into the capsule, wherein the capsule comprises an aluminum capsule body having a central capsule body axis, said aluminum capsule body being provided with a capsule body bottom, a side wall and an outwardly extending flange comprising a curled outer edge, said outwardly extending flange extending transverse to the central capsule body axis, the capsule further comprising an aluminum cover attached to the outwardly extending flange, the cover hermetically closing the capsule, wherein the capsule further comprises a sealing member at the outwardly extending flange for providing a fluid sealing contact with an enclosing member of a beverage preparation device if the capsule is positioned in the enclosing member of the beverage preparation device and the enclosing member is closed by means of a closing member of the beverage preparation device, such as an extraction plate of the beverage preparation device, such that the outwardly extending flange of the capsule and at least a portion of the sealing member of the capsule are sealingly engaged between the enclosing member and the closing member of the beverage preparation device, wherein the enclosing member of the beverage preparation device comprises an annular element having a central annular element axis and a free contact end, characterized in that, the sealing member is integral with the outwardly extending flange and comprises a single annular projection comprising a projection top projecting axially towards the capsule body bottom from an inner foot portion radially outside of a flat inner flange portion extending between the capsule body side wall and the projection and an outer foot portion radially inside of a flat outer flange portion extending between the projection and the curled outer edge, and wherein the flat outer flange portion and the flat inner flange portion are in line and wherein a radially outer wall of said projection is oriented transverse to the flat outer flange portion, wherein the curled outer edge axially extends at both sides of the flat outer flange portion,, wherein the cover is attached to the flat outer flange portion wherein the capsule comprises a bearing for the enclosing member if the capsule is positioned in the enclosing member and the enclosing member is closed by means of the closing member, said bearing being formed by at least the projection, wherein the thickness of the aluminum capsule body is between 80 micrometer to 110 micrometer, such that it is deformed easily if the capsule is positioned in the enclosing member of the beverage preparation device and the enclosing member is closed by means of the closing member of the beverage preparation device, wherein the thickness of the aluminum cover is 15 to 65 micrometer, preferably 30-45 micrometer and more preferably 39 micrometer, wherein the aluminum cover is arranged to tear open on the closing member of the beverage preparation device, such as an extraction plate of the beverage preparation device under the influence of fluid pressure in the capsule, wherein the height of the sealing member portion to be contacted first by the free contact end of the enclosing member when the enclosing member is closed is at least 0.8 mm and at most 2 mm, wherein the sealing member and the remainder of the capsule body are made of the same plate material; wherein the projection has an extreme top end extending around the capsule body axis at a diameter of 31.9 to 32.4 mm.