Abstract: An actuator arrangement for use in a fuel injector of an internal combustion engine, including an inner core (40) comprising a collar (48) and a core region (44) having a plurality of laminates (140) stacked in the direction of a first lamination axis (LA) and a first outer pole (42) for receiving at least a part of the core region (44). An electromagnetic winding (52) is received within a first volume defined between the first outer pole (42) and the core region (44). The collar (48) is formed from at least two collar parts (48a, 48b) which are adjustable relative to one another to alter the separation between them so as to accommodate core regions (44) of different diameter. The collar (48) is formed from a plurality of laminates (1, 2, 3, 4, 5) having a second lamination axis (A) which is perpendicular to the first lamination axis (LA).