An injection device with a luer fitting, the injection device comprising: a compressible syringe body comprising two flexible sheets of thermoplastic material defining a reservoir; a male luer fitting that is substantially cylindrical having a tapered outer surface, a base end and a luer tip at an end of said male luer fitting opposing said base end, said base end connected to said syringe body, said male luer fitting having a channel therethrough for conducting contents of the reservoir; a first connecting structure arranged on said tapered outer surface of the male luer fitting between said base end and said luer tip; a shield cap having a generally cylindrical shaped portion arranged on the male luer fitting at a first position relative to said male luer fitting prior to use of the injection device, said shield cap having a second connecting structure on an inner surface of its generally cylindrical shaped portion and interacting with said first connecting structure to prevent inadvertent movement of said shield cap relative to said male luer fitting when said shield cap is arranged at said first position; a first seal, said first seal sealing said channel at said luer tip; and a second seal between said shield cap and said male luer fitting sealing the tapered outer surface and the luer tip of said male luer fitting from outside contamination, said second seal formed by said first and second connecting structures when the shield cap is arranged at the first position, in which the first connecting structure is formed on the luer tip of said male luer fitting between said base end and said luer tip_and the second connecting structure is formed on said shield cap, and in which said first and second connecting structures are ribs that form a tortuous path to create said second seal when the shield cap encloses the male luer fitting in the first position, wherein the first and second connecting structures prevent inadvertent movement of the shield cap relative to the male luer fitting when the shield cap is arranged in the first position; wherein said shield cap is movable relative to said male luer fitting to a second position from said first position to break one or both of the first seal and the second seal so that the male luer fitting is capable of delivering the contents of the reservoir after the shield cap is removed from the male luer fitting from the second position, wherein said first seal being broken by movement of said shield cap from said first position to said second position, characterized in that said first seal is formed as a twist-off tab, an end of said twist-off tab being received in a recess formed in said shield cap when said shield cap is in said first position to prevent leakage therethrough of content from said reservoir at least when the shield cap is at said first position. a compressible syringe body comprising two flexible sheets of thermoplastic material defining a reservoir; a male luer fitting that is substantially cylindrical having a tapered outer surface, a base end and a luer tip at an end of said male luer fitting opposing said base end, said base end connected to said syringe body, said male luer fitting having a channel therethrough for conducting contents of the reservoir; a first connecting structure arranged on said tapered outer surface of the male luer fitting between said base end and said luer tip; a shield cap having a generally cylindrical shaped portion arranged on the male luer fitting at a first position relative to said male luer fitting prior to use of the injection device, said shield cap having a second connecting structure on an inner surface of its generally cylindrical shaped portion and interacting with said first connecting structure to prevent inadvertent movement of said shield cap relative to said male luer fitting when said shield cap is arranged at said first position; a first seal, said first seal sealing said channel at said luer tip; and a second seal between said shield cap and said male luer fitting sealing the tapered outer surface and the luer tip of said male luer fitting from outside contamination, said second seal formed by said first and second connecting structures when the shield cap is arranged at the first position, in which the first connecting structure is formed on the luer tip of said male luer fitting between said base end and said luer tip_and the second connecting structure is formed on said shield cap, and in which said first and second connecting structures are ribs that form a tortuous path to create said second seal when the shield cap encloses the male luer fitting in the first position, wherein the first and second connecting structures prevent inadvertent movement of the shield cap relative to the male luer fitting when the shield cap is arranged in the first position; wherein said shield cap is movable relative to said male luer fitting to a second position from said first position to break one or both of the first seal and the second seal so that the male luer fitting is capable of delivering the contents of the reservoir after the shield cap is removed from the male luer fitting from the second position, wherein said first seal being broken by movement of said shield cap from said first position to said second position, characterized in that said first seal is formed as a twist-off tab, an end of said twist-off tab being received in a recess formed in said shield cap when said shield cap is in said first position to prevent leakage therethrough of content from said reservoir at least when the shield cap is at said first position.