The Tiffen #87 Infrared Glass Filter is for black and white infrared film when you only want to transmit the infrared spectrum and none of the visible spectrum.
Tiffen filters are not dyed but are manufactured by using ColorCore technology. This process laminates the filter material between two pieces of optical glass and grinds down and polishes the glass. The glass is then mounted to the metal ring, which after that can be screwed onto the lens for the desired effect.
