an injection device body;

a plunger comprising one or more plunger recesses;

biasing means for applying a biasing force to bias the plunger in a distal direction of the injection device;

a casing at least partially enclosing the plunger, the casing comprising one or more toothed beams each comprising a tooth engageable with a corresponding plunger recess of the one or more plunger recesses; and

a rotatable collar at least partially enclosing the casing and comprising one or more collar recesses on an inner surface of the rotatable collar; and

wherein:

each of the one or more plunger recesses is shaped to urge the tooth of the corresponding toothed beam outwards when the biasing force is applied to the plunger in a pre-use configuration; and

the one or more collar recesses are shaped to cooperate with a tooth of the corresponding toothed beam to apply a torque to the rotatable collar when the corresponding toothed beam is urged outwards in the pre-use configuration.