A clip for securing a sleeve to the body of a piezoelectric actuator in an actuator assembly. The clip takes the form of a band and has at least a first and a second stable state. The minimum separation of the walls of the band when the clip is in one of the stable states is less than the minimum separation of the walls of the band when the clip is in an unstable state. The clip is forced into an unstable state in order to be fitted over the sleeve of the actuator assembly. The force is then removed to allow the clip to revert towards a stable state. The dimensions of the clip are such that the clip is unable to fully revert to a stable state when fitted to the actuator assembly thereby maintaining sufficient additional strain energy to maintain a sufficient clamping force between the sleeve and the body of the actuator.