For the 1920s Investigators' Companion Volume 1 Equipment & Resources.
From the back cover:
Hot Tips, Secret Info, & Sure-Fire Rules
Are there flashlights in the 1920s? How about flashbulbs? What can your licensed private-eye do? Can your investigator buy a machine gun?
Too often, Call of Cthulhu investigators find themselves not only baffled by the mysteries of the Mythos, but baffled as well by the day-to-day life in America during the Roaring Twenties.
Discover the types of research facilities that are available, learn new skills, and purchase a variety of types of equipment including an extensive list of firearms common to the era. Consult with experts on a variety of esoteric and occult topics.
An essential aid for players, investigators, and Keepers.