Safety device for a pre-filled syringe and injection device

An injection device (D) comprising a pre-filled syringe with a hypodermic needle attached to a distal end of the pre-filled syringe and

• a safety device for the pre-filled syringe, wherein the safety device comprises
• a substantially cylindrical and hollow support body comprising at least one resilient arm having an inner surface and
• a hollow needle shield slideably arranged relative to the support body, wherein the needle shield comprises at least one curved actuation ramp having an outside surface protruding in a lateral direction (L) perpendicular to a central axis (A) of the safety device, characterized in that the curved actuation ramp comprises a first lateral dimension (L1) at a proximal end of the needle shield and a second lateral dimension (L2) exceeding the first lateral dimension (L1) at a distal end of the needle shield, wherein the inner surface of the resilient arm engages the outside surface of the curved actuation ramp when the needle shield is slid relative to the support body,
• wherein the hypodermic needle protrudes the distal end of the support body and is surrounded by the needle shield in an initial position (I) and/or in an advanced position (III),
• characterized in that the needle shield is slideable with respect to the support body from the initial position (I) to a retracted position (II) and further to the advanced position (III), wherein the needle shield protrudes the support body in the initial position (I) and in the advanced position (III) and
• whereas the needle shield is substantially received within the support body in the retracted position (II).