(click on pictures to enlarge)
The Swanberg Manufacturing Company was located in Chicago, Illinois. The two metal pencils are lightweight aluminum pencils, and are marked "Swanberg Pats. Pend."
The black model is marked "Swanberg Made in USA Under the Keeran-Chelton Pats. Pend."
Pencil fans recognize Charles Keeran as the inventor of the Eversharp Pencil, as well as for his involvement with Autopoint and Dur-O-Lite, not to mention his namesake Keeran Products Co. Less well known is that in the late 1920s, he also had a relationship with Swanberg. The reference to "Keeran-Chelton" is to patent number 1,774,699, issued to Robert Chelton and Charles R. Keeran on September 2, 1930. View patent here. Since this patent was applied for on February 14, 1927, we can date this pencil to between 1927 and 1930.
Keeran also invented a clip, patent number 1,700,410 which was assigned to Swanberg. View here.