This filter cube is new "old stock" from a former Nikon dealer inventory. It will fit the Nikon Eclipse series of fluorescent microscopes, E400/600/800, and TE200/300 Inverted. It is in the catalog with a product number of 96150. The list price is $1,293.00.  The cube is in new condition and still in its' plastic bubble case.. 

Blue Excitation Filter Block B-1E (Blue) Specifications:

• Excitation Filter Wavelengths: 470-490 nanometers 

• Dichromatic Mirror Cut-on Wavelength: 505 nanometers 

• Barrier Filter Wavelengths: 520-560 nanometer 

The B-1E filter combination is one of three sets in the blue fluorescence excitation series that utilize bandpass, as opposed to longpass, barrier filters, and which differ primarily in the width of the excitation band. Each of the bandpass barrier filter sets provides performance suitable for imaging specimens labeled with fluorescein isothiocyanate (FITC) (green emission), while blocking yellow, orange, and red emission. The B-1E combination uses a narrow-bandpass excitation filter in conjunction with the bandpass emission (barrier) filter.