Aspects of the disclosure relate to a games controller for controlling electronic games, input device for a computer program and a trigger mechanism therefor. The trigger mechanism comprises a trigger body having a plurality of walls defining an internal chamber. The plurality of walls include a base wall and an orifice defined in the base wall. A detent is detachably mounted on the trigger body. The detent is at least partially received in the orifice and the detent is rotatable with respect to the trigger body. The detent comprises at least one abutment surface which is eccentrically arranged with respect to the rotational axis of the detent.