This B&W Series 7 093 (87C) Infrared Glass Filter blocks the entire visible spectrum, so to our eyes it looks completely opaque. Unlike the B&W 092 infrared filter, it makes pure infrared photographs possible without the visible red component.
Its transmission only begins to exceed 1% at 800 nm, rising to 88% at 900 nm, and remains that high far beyond the upper limit of sensitization covered by infrared films
This filter is used less frequently in pictorial photography because of the dramatic loss of effective ISO
In the scientific field, materials research and forensics, the limitation to a strictly infrared range is often important