This Kodak 4 x 4" #98 Blue Wratten Gel Filter for Black & White Film is equivalent to a #47B (deep blue) filter plus a #2B (pale yellow) filter. It is used for making separation positives from color negative films. Also used in three-color printing on color papers.
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), 14 x 18" (350 x 450mm) and 4 x 12" (10.2 x 30.5cm).