All About Pocket Knives

How old is this flea market find? What is the handle material and/or color scheme called?
So far I’ve found that it’s called a slender serpentine jack. #15 is stamped on the tang of the main blade.

1946-55 short line stamp celluloid handles.

Thanks Greg

1946 Catalog Cut. (left click on it to enlarge) Pyroxylin was the Camillus name for Celluloid. Still in catalogs until sometime before 1965 but the handle color had changed around 1955 from Red to Maize (yellow). Greg is most likely correct on the dates of manufacture for the 15 with red handles.