SPI Pore 5.0 µm 25 mm Diameter Black Polycarbonate Track Etch Membrane Filters Pack of 100

Common uses for the "black" membrane filters include all previously mentioned applications for polycarbonate membrane filters except in this case, the samples are going to be viewed with some type of fluorescence-type microscopy, such as epifluorescence, and in that kind of situation, the desired background is to be pitch black. The filters are actually gray in color but appear to be black under reflected light.

Who else might find the black membranes useful?
Almost all users specify and use the standard "white" membranes. The "black" membranes are dark in color, and certain types of particles are easier to see in a reflected light microscope when this type of filter is used. 

SPI offers the black membrane filters only in the SPI-Pore brand of polycarbonate track etch membrane filters.

Holding the membrane filters:
All membrane filters, offered by SPI Supplies, irrespective of their construction, must be used in conjunction with a specially made membrane filter holder.

Note:
All SPI-Pore™ Black Polycarbonate Track Etch membranes are offered only in packages of 100 each.