I claim the ornamental design for an injection device, as shown and described.
FIG. 1 is a front view of the injection device;
FIG. 2 is a first side view of the injection device;
FIG. 3 is a top view of the injection device;
FIG. 4 is a bottom of the injection device;
FIG. 5 is a back view of the injection device;
FIG. 6 is a second side view of the injection device;
FIG. 7 is a perspective view of the injection device with a needle attached with the collar part of the device shown in a second position; and,
FIG. 8 is a perspective view of the injection device with the collar part of the device shown in the second position.
The broken line showing of the needle in FIG. 7 is included for the purpose of illustrating environmental structure and forms no part of the claimed design. The broken line showing of the spaces around the detent in FIG. 1 is included for the purpose of illustrating portions of the article that form no part of the claimed design.