Isotopes (bone seekers no less) sent in the mail to children!
The set came with four types of uranium ore, a beta-alpha source (Pb-210), a pure beta source (Ru-106), a gamma source (Zn-65),a spinthariscope, a cloud chamber with its own short-lived alpha source (Po-210), an electroscope, a Geiger counter, a manual, a comic book (Dagwood Splits the Atom) and a government manual "Prospecting for Uranium."
Other Gilbert sets (e.g., the No. 11 Atomic Energy set) continued to carry the spinthariscope, the ore and the manual.
In addition, the Geiger counter could be purchased separately.