The present invention relates to a supplementary device for a manually operable injection device, the supplementary device comprising:- a body (300) having at least one engaging member (340) to releasably mount the body (300) to the injection device (1) in a specific position (P) on an outside surface (106) of the injection device (1),- at least one indicator (350 370 380) located on the body (300) and having a shape or contour to overlap or to align with a mark (150 160 170 180) on the outside surface (106) of the injection device (1) when the body (300) is in or near the specific position (P).
