Volpi Blue Fiber Optic Illuminator Filter. The filter fits into the provided slot of some earlier Nikon lamp supply units and also into the Volpi Inaterlux 4000-1, 5000-1 and 6000-1 lamp supply units. The filter is the standard NCB-11 Blue with dimensions of 5.74 mm thick, 26.25 mm wide and 50.41 mm length for insertion depth. This item is new still in original packing. Thanks for looking!