Kodak 3 x 3" (75 x 75mm) #87B Opaque Infrared Wratten Gel Filter - This black infrared filter will filter out the entire visible spectrum. It is used with black and white infrared film with a sensitivity up to approximately 1000nm. Filter factor is determined by the film sensitivity.
Most Kodak gelatin filters are available in 3 x 3" (75 x 75mm), 4 x 4" (100 x 100mm), 6 x 6" (150 x 150mm), and 14 x 18" (350 x 450mm).