A collapsible occlusion device (1, 180) suitable for occluding an atrial appendage and comprising a mesh or braiding of more than one wire or thread, wherein said mesh or braiding comprises: a proximal retention region at a proximal end of the occlusion device; wherein, in the expanded state of said device, the proximal retention region has a disc shape, and a distal retention region; and a central region between said proximal retention region and said distal retention region, wherein: the occlusion device has a closed distal end without a hub for said more than one wire or thread; said mesh or braiding has been given a predetermined, shape in an expanded state using a reshaping and/or heat treatment process; the occlusion device is self-expandable in an atrial appendage from a collapsed state to said expanded state in which the proximal retention region is configured to occlude an opening into an atrial appendage and the distal retention region is configured to engage internal walls of the atrial appendage under radial pretension to retain the expanded occlusion device in position; and wherein the proximal retention region has a holder or hub in which ends of the wires or threads of the mesh or braiding meet, wherein the central region, in the expanded state of said device, is a waisted, cylindrical section providing flexibility of motion between the proximal and distal retention regions (2,3) in relation to each other; and wherein the predetermined shape of said distal retention region is a hollow portion of the mesh or braiding with a circular cross section that gradually tapers towards said closed distal end; or wherein the predetermined shape of said distal retention region has a bell-like shape formed by said distal retention region being flared back on itself and said bell-like shape has a tapering end forming said distal retention region. a proximal retention region at a proximal end of the occlusion device; wherein, in the expanded state of said device, the proximal retention region has a disc shape, and a distal retention region; and a central region between said proximal retention region and said distal retention region, wherein: the occlusion device has a closed distal end without a hub for said more than one wire or thread; said mesh or braiding has been given a predetermined, shape in an expanded state using a reshaping and/or heat treatment process; the occlusion device is self-expandable in an atrial appendage from a collapsed state to said expanded state in which the proximal retention region is configured to occlude an opening into an atrial appendage and the distal retention region is configured to engage internal walls of the atrial appendage under radial pretension to retain the expanded occlusion device in position; and wherein the proximal retention region has a holder or hub in which ends of the wires or threads of the mesh or braiding meet, wherein the central region, in the expanded state of said device, is a waisted, cylindrical section providing flexibility of motion between the proximal and distal retention regions (2,3) in relation to each other; and wherein the predetermined shape of said distal retention region is a hollow portion of the mesh or braiding with a circular cross section that gradually tapers towards said closed distal end; or wherein the predetermined shape of said distal retention region has a bell-like shape formed by said distal retention region being flared back on itself and said bell-like shape has a tapering end forming said distal retention region. the occlusion device has a closed distal end without a hub for said more than one wire or thread; said mesh or braiding has been given a predetermined, shape in an expanded state using a reshaping and/or heat treatment process; the occlusion device is self-expandable in an atrial appendage from a collapsed state to said expanded state in which the proximal retention region is configured to occlude an opening into an atrial appendage and the distal retention region is configured to engage internal walls of the atrial appendage under radial pretension to retain the expanded occlusion device in position; and wherein the proximal retention region has a holder or hub in which ends of the wires or threads of the mesh or braiding meet, wherein the central region, in the expanded state of said device, is a waisted, cylindrical section providing flexibility of motion between the proximal and distal retention regions (2,3) in relation to each other; and wherein the predetermined shape of said distal retention region is a hollow portion of the mesh or braiding with a circular cross section that gradually tapers towards said closed distal end; or wherein the predetermined shape of said distal retention region has a bell-like shape formed by said distal retention region being flared back on itself and said bell-like shape has a tapering end forming said distal retention region.