An earpiece for an ear, said ear comprising a concha cavity at least partially delimited by a concha floor, a concha side wall and a concha ceiling, wherein said concha side wall connects said concha floor to said concha ceiling, wherein the surface of said concha ceiling has a normal at least a component of which being directed towards said concha floor, said earpiece comprising a peripheral skirt comprising a positioning skirt portion which in turn comprises an outer skirt surface and an inner skirt surface, wherein a transition from said outer skirt surface to said inner skirt surface occurs at a skirt edge, wherein said skirt edge extends at least partially circumferentially around a central axis of said earpiece, wherein said earpiece is adapted to be moved to a use position, at least partially within said concha cavity, in a direction parallel to said central axis, during insertion of said earpiece into said ear, wherein, when said peripheral skirt is in a non-influenced condition, at least a portion of said inner skirt surface faces said central axis, wherein said earpiece is such that said positioning skirt portion is adapted to assume said use position at least partially within said concha cavity whereby: - at least a portion of said outer skirt surface abuts at least a portion of said concha ceiling, - said skirt edge is located closer to said concha floor than said outer skirt surface, and - said skirt edge is spaced from said concha floor, wherein: - said earpiece further comprises a movement-prevention member (80; 86) adapted to prevent said positioning skirt portion from moving relative to said concha floor to a position in which at least a portion of said skirt edge contacts said concha floor, and wherein as seen in a plane defined by said central axis and a radial axis being perpendicular to said central axis, said positioning skirt portion comprises a segment, extending between two distinct positions (37', 37") along said radial axis, being such that, when said peripheral skirt is in said non-influenced condition, each one of said inner skirt surface and said outer skirt surface associated with said segment is located on the same side of said skirt edge, as seen along said central axis. said earpiece comprising a peripheral skirt comprising a positioning skirt portion which in turn comprises an outer skirt surface and an inner skirt surface, wherein a transition from said outer skirt surface to said inner skirt surface occurs at a skirt edge, wherein said skirt edge extends at least partially circumferentially around a central axis of said earpiece, wherein said earpiece is adapted to be moved to a use position, at least partially within said concha cavity, in a direction parallel to said central axis, during insertion of said earpiece into said ear, wherein, when said peripheral skirt is in a non-influenced condition, at least a portion of said inner skirt surface faces said central axis, wherein said earpiece is such that said positioning skirt portion is adapted to assume said use position at least partially within said concha cavity whereby: - at least a portion of said outer skirt surface abuts at least a portion of said concha ceiling, - said skirt edge is located closer to said concha floor than said outer skirt surface, and - said skirt edge is spaced from said concha floor, - at least a portion of said outer skirt surface abuts at least a portion of said concha ceiling, - said skirt edge is located closer to said concha floor than said outer skirt surface, and - said skirt edge is spaced from said concha floor, wherein: - said earpiece further comprises a movement-prevention member (80; 86) adapted to prevent said positioning skirt portion from moving relative to said concha floor to a position in which at least a portion of said skirt edge contacts said concha floor, and wherein - said earpiece further comprises a movement-prevention member (80; 86) adapted to prevent said positioning skirt portion from moving relative to said concha floor to a position in which at least a portion of said skirt edge contacts said concha floor, and wherein as seen in a plane defined by said central axis and a radial axis being perpendicular to said central axis, said positioning skirt portion comprises a segment, extending between two distinct positions (37', 37") along said radial axis, being such that, when said peripheral skirt is in said non-influenced condition, each one of said inner skirt surface and said outer skirt surface associated with said segment is located on the same side of said skirt edge, as seen along said central axis.