A fastening device for fastening soft surfaced elements to each other, wherein the device comprises: - a planar top portion, - two side portions (102, 103), each of which is coupled with said planar portion at one end, • said side portions being arranged essentially perpendicularly in relation to said planar top portion and essentially parallel with each other thereby forming a receiving opening for receiving said element between the side portions, and • said side portions both comprise at least one tooth, which is inclined towards the opening and the element in use and thereby arranged to fasten into the surface of the element and thereby fasten the device to the element, wherein - the top planar portion comprises a protrusion portion for receiving, focusing and attaching a magnetic member to the device so to allow the device to be fastened to an external member via said magnetic member, and - said device comprises an angle portion between said planar top portion and side portion (102, 103), wherein said angle portion is inclined to extending towards said opening and intersecting a normal of said top planar portion at least in an end portion of said planar portion, whereupon the extent of the inclined angle portion determines the size of the opening for receiving the element, wherein - each of the side portions (102, 103) comprise the protrusion portion for receiving, focusing and attaching the magnetic member to the device so to allow the device to be fastened to the external member via said magnetic member, and - a surface of the protrusion portion is elevated from a surface of the top planar portion and each of the side portions (102, 103). - a planar top portion, - two side portions (102, 103), each of which is coupled with said planar portion at one end, • said side portions being arranged essentially perpendicularly in relation to said planar top portion and essentially parallel with each other thereby forming a receiving opening for receiving said element between the side portions, and • said side portions both comprise at least one tooth, which is inclined towards the opening and the element in use and thereby arranged to fasten into the surface of the element and thereby fasten the device to the element, wherein • said side portions being arranged essentially perpendicularly in relation to said planar top portion and essentially parallel with each other thereby forming a receiving opening for receiving said element between the side portions, and • said side portions both comprise at least one tooth, which is inclined towards the opening and the element in use and thereby arranged to fasten into the surface of the element and thereby fasten the device to the element, - the top planar portion comprises a protrusion portion for receiving, focusing and attaching a magnetic member to the device so to allow the device to be fastened to an external member via said magnetic member, and - said device comprises an angle portion between said planar top portion and side portion (102, 103), wherein said angle portion is inclined to extending towards said opening and intersecting a normal of said top planar portion at least in an end portion of said planar portion, whereupon the extent of the inclined angle portion determines the size of the opening for receiving the element, - each of the side portions (102, 103) comprise the protrusion portion for receiving, focusing and attaching the magnetic member to the device so to allow the device to be fastened to the external member via said magnetic member, and - a surface of the protrusion portion is elevated from a surface of the top planar portion and each of the side portions (102, 103).