A coupler is configured to couple an implement to an earth moving or materials handling machine. The coupler includes a locking member for locking a pin of an implement into a coupler in the recess. The locking member is driven by a hydraulic arrangement, with the hydraulic cylinder body being formed integrally with either the coupler body or the locking member. The coupler may be adapted to accommodate a range of implement pin spacings and/or diameters, so that the coupler can be used with different implements and in particular with different makes of implement.