An oral care refill head (200, 400) for detachable coupling to a stem (120, 320) of a handle (100, 300), the oral care refill head (200, 400) comprising: an oral care treatment portion (210, 410); and a sleeve portion (220, 420) comprising: a sleeve cavity (221, 421) extending along a cavity axis; a sleeve interference section (223, 423); a sleeve snap element (225, 425); and a proximal edge surface (222, 422) that defines an opening into the sleeve cavity (221, 421), the proximal edge surface (222, 422) of the sleeve portion (220, 420) extending radially from an outer sleeve edge to an inner sleeve edge, the proximal edge surface (222, 422) inclined from the inner sleeve edge to the outer sleeve edge in one direction either upwardly towards the oral treatment portion or downwardly away from oral treatment portion with increasing distance from the cavity axis; characterized in that: the sleeve portion (220, 420) comprises a sleeve rotational alignment element (226, 426); and wherein the sleeve rotational alignment element (226, 426) comprises a sleeve groove in an inner surface of the sleeve portion (220, 420) that defines the sleeve cavity (221, 421), the sleeve groove extending axially from an open groove end in the proximal edge of the sleeve portion (220, 420) to a closed groove end wall, in particular wherein the sleeve snap element (225, 425) comprises a sleeve ring that protrudes from the inner surface of the sleeve portion (220, 420) and extends circumferentially around the inner surface of the sleeve portion (220, 420); and the sleeve portion (220, 420) further comprises an outer surface which does not comprise any openings, apertures, or slits. an oral care treatment portion (210, 410); and a sleeve portion (220, 420) comprising: a sleeve cavity (221, 421) extending along a cavity axis; a sleeve interference section (223, 423); a sleeve snap element (225, 425); and a proximal edge surface (222, 422) that defines an opening into the sleeve cavity (221, 421), the proximal edge surface (222, 422) of the sleeve portion (220, 420) extending radially from an outer sleeve edge to an inner sleeve edge, the proximal edge surface (222, 422) inclined from the inner sleeve edge to the outer sleeve edge in one direction either upwardly towards the oral treatment portion or downwardly away from oral treatment portion with increasing distance from the cavity axis; characterized in that: the sleeve portion (220, 420) comprises a sleeve rotational alignment element (226, 426); and wherein the sleeve rotational alignment element (226, 426) comprises a sleeve groove in an inner surface of the sleeve portion (220, 420) that defines the sleeve cavity (221, 421), the sleeve groove extending axially from an open groove end in the proximal edge of the sleeve portion (220, 420) to a closed groove end wall, in particular wherein the sleeve snap element (225, 425) comprises a sleeve ring that protrudes from the inner surface of the sleeve portion (220, 420) and extends circumferentially around the inner surface of the sleeve portion (220, 420); and the sleeve portion (220, 420) further comprises an outer surface which does not comprise any openings, apertures, or slits. a sleeve cavity (221, 421) extending along a cavity axis; a sleeve interference section (223, 423); a sleeve snap element (225, 425); and a proximal edge surface (222, 422) that defines an opening into the sleeve cavity (221, 421), the proximal edge surface (222, 422) of the sleeve portion (220, 420) extending radially from an outer sleeve edge to an inner sleeve edge, the proximal edge surface (222, 422) inclined from the inner sleeve edge to the outer sleeve edge in one direction either upwardly towards the oral treatment portion or downwardly away from oral treatment portion with increasing distance from the cavity axis; characterized in that: the sleeve portion (220, 420) comprises a sleeve rotational alignment element (226, 426); and wherein the sleeve rotational alignment element (226, 426) comprises a sleeve groove in an inner surface of the sleeve portion (220, 420) that defines the sleeve cavity (221, 421), the sleeve groove extending axially from an open groove end in the proximal edge of the sleeve portion (220, 420) to a closed groove end wall, in particular wherein the sleeve snap element (225, 425) comprises a sleeve ring that protrudes from the inner surface of the sleeve portion (220, 420) and extends circumferentially around the inner surface of the sleeve portion (220, 420); and the sleeve portion (220, 420) further comprises an outer surface which does not comprise any openings, apertures, or slits. the sleeve portion (220, 420) comprises a sleeve rotational alignment element (226, 426); and wherein the sleeve rotational alignment element (226, 426) comprises a sleeve groove in an inner surface of the sleeve portion (220, 420) that defines the sleeve cavity (221, 421), the sleeve groove extending axially from an open groove end in the proximal edge of the sleeve portion (220, 420) to a closed groove end wall, in particular wherein the sleeve snap element (225, 425) comprises a sleeve ring that protrudes from the inner surface of the sleeve portion (220, 420) and extends circumferentially around the inner surface of the sleeve portion (220, 420); and the sleeve portion (220, 420) further comprises an outer surface which does not comprise any openings, apertures, or slits.