Injection device for dispensing a medicament, comprising: a cartridge module, a dispensing mechanism which is actuated to dispense the injectable preparation, a dose-setting mechanism for setting the dose at which the injectable preparation is dispensed when the dispensing mechanism is actuated, the dose-setting mechanism comprising: a housing part (11) in which at least part of the dispensing mechanism is received, a display sleeve (13) rotatable therein, and an insertion sleeve (15) that can be inserted into the housing part (11), wherein the insertion sleeve (15) has, on its outer face, a raised surface section (20) that is transparent at least in some areas, and the housing part (11) has a recess (25) which is open at its distal edge (24) and which receives the insertion sleeve (15) in a rotationally fixed manner from the direction of the open end of the recess (25), and insertion sleeve for an injection device, dose-setting mechanism for an injection device for dispensing a medicament, and method for assembling an injection device.