An attachment device for attaching a prosthesis to implants in a stump, said attachment device comprising: a base plate having an extension in an xy-plane; a first holder for holding a first abutment; a second holder for holding a second abutment, the first and second abutments being configured to be implanted in a stump; a locking element connected to said base plate and configured to restrict movement of said holders in a z-direction away from said base plate by means of an opening in the locking element, in the xy-plane, smaller than a diameter of a lower portion of the holder (106, 108), the opening having an elongated shape to allow for movement in the x direction of the respective holder, said lower portion of the holder (106, 108) being arranged between said base plate and said locking element in the z-direction, said first and second holder each comprises a first lower portion having a first diameter and a second upper portion having a second diameter, said first diameter being larger than said second diameter and wherein said lower portion is arranged nearest said base plate such that said lower portion engages said locking element to restrict movement of said holder in said z-direction, wherein said locking element is further configured to allow rotation of said first and second holder around a z-axis perpendicular to said xy-plane, wherein said locking element and said base plate are further configured to allow movement of said first holder along an x-direction of said base plate and to prevent movement of said first holder in an y-direction by means of side walls (104a, 104c) extending in said z-direction from said base plate and to prevent movement of said second holder in said x-direction and in said y-direction by means of a side wall and a dividing wall 122 extending in said z-direction from said base plate; and at least one flexible member (126, 128) arranged between each of said first and second holders and said base plate, said flexible member being flexible in said z-direction and configured to allow a movement of said first and second holder in said z-direction in relation to said base plate and to allow said first and second holder to tilt with respect to said xy-plane of said base plate. a base plate having an extension in an xy-plane; a first holder for holding a first abutment; a second holder for holding a second abutment, the first and second abutments being configured to be implanted in a stump; a locking element connected to said base plate and configured to restrict movement of said holders in a z-direction away from said base plate by means of an opening in the locking element, in the xy-plane, smaller than a diameter of a lower portion of the holder (106, 108), the opening having an elongated shape to allow for movement in the x direction of the respective holder, said lower portion of the holder (106, 108) being arranged between said base plate and said locking element in the z-direction, said first and second holder each comprises a first lower portion having a first diameter and a second upper portion having a second diameter, said first diameter being larger than said second diameter and wherein said lower portion is arranged nearest said base plate such that said lower portion engages said locking element to restrict movement of said holder in said z-direction, wherein said locking element is further configured to allow rotation of said first and second holder around a z-axis perpendicular to said xy-plane, wherein said locking element and said base plate are further configured to allow movement of said first holder along an x-direction of said base plate and to prevent movement of said first holder in an y-direction by means of side walls (104a, 104c) extending in said z-direction from said base plate and to prevent movement of said second holder in said x-direction and in said y-direction by means of a side wall and a dividing wall 122 extending in said z-direction from said base plate; and at least one flexible member (126, 128) arranged between each of said first and second holders and said base plate, said flexible member being flexible in said z-direction and configured to allow a movement of said first and second holder in said z-direction in relation to said base plate and to allow said first and second holder to tilt with respect to said xy-plane of said base plate.