Attachment for a personal care device, the attachment comprising: - at least one treatment member for performing a treatment action, and - a coupling member for releasably coupling the attachment to a coupling structure of a main housing of the personal care device, wherein - the coupling member comprises a shaft-like element: - having a circumferential surface and a central axis, - protruding from the attachment in a direction away from the at least one treatment member, and - comprising at least one coupling recess arranged in a portion of the circumferential surface which is convex at least when seen in a cross-section of the shaft-like element perpendicular to the central axis, characterized in that: - the at least one coupling recess, when seen in the cross-section of the shaft-like element perpendicular to the central axis, has a central portion and first and second side portions (18, 20) arranged on opposite sides of the central portion and each extending from the central portion up to an end point (19, 19') of the coupling recess, and - the at least one coupling recess comprises a sloped surface arranged in at least the central portion, said sloped surface being inclined towards the treatment member seen in a direction from the circumferential surface towards the central axis, and wherein - at least one of the first and second side portions (18, 20) of the coupling recess is recessed relative to the sloped surface, seen in a direction parallel to the central axis. - at least one treatment member for performing a treatment action, and - a coupling member for releasably coupling the attachment to a coupling structure of a main housing of the personal care device, wherein - the coupling member comprises a shaft-like element: - having a circumferential surface and a central axis, - protruding from the attachment in a direction away from the at least one treatment member, and - comprising at least one coupling recess arranged in a portion of the circumferential surface which is convex at least when seen in a cross-section of the shaft-like element perpendicular to the central axis, characterized in that: - the at least one coupling recess, when seen in the cross-section of the shaft-like element perpendicular to the central axis, has a central portion and first and second side portions (18, 20) arranged on opposite sides of the central portion and each extending from the central portion up to an end point (19, 19') of the coupling recess, and - the at least one coupling recess comprises a sloped surface arranged in at least the central portion, said sloped surface being inclined towards the treatment member seen in a direction from the circumferential surface towards the central axis, and wherein - at least one of the first and second side portions (18, 20) of the coupling recess is recessed relative to the sloped surface, seen in a direction parallel to the central axis. - the at least one coupling recess, when seen in the cross-section of the shaft-like element perpendicular to the central axis, has a central portion and first and second side portions (18, 20) arranged on opposite sides of the central portion and each extending from the central portion up to an end point (19, 19') of the coupling recess, and - the at least one coupling recess comprises a sloped surface arranged in at least the central portion, said sloped surface being inclined towards the treatment member seen in a direction from the circumferential surface towards the central axis, and wherein - at least one of the first and second side portions (18, 20) of the coupling recess is recessed relative to the sloped surface, seen in a direction parallel to the central axis.