Found these on eBay - No connection to me.
http://www.ebay.com/itm/Vintage-1926-TUNG-SOL-Blue-AUTOMOBILE-HEAD-LIGHT-LAMPS-1 0-in-Box-NOS-car-bulb-/371536538694?hash=item56814dac46:g:hFMAAOSwYHxWJCaC&vxp=m tr
The packaging of things in that era is pretty darn fun to see.
Interesting. I have a box of bulbs like that but the end with the voltage markings was missing.
From what I understand 1915 and 1916 were series wired 9 volt bulbs. The bulb was a double contact with single filament. I further believe that the same wiring method continued up to 1918. When the battery and starter was introduced in 1919 the head lamps were wired parallel and the bulbs were double contact and double filament with high and low beam offered. If the package is dated 1926 I would expect the lamps to be 6 volts. Throughout the years there have been a variety of after market wiring methods. Up to 1926 if the car was ordered non electric then perhaps the head light bulbs may still have been 9 volts, and with a battery may have been 6 volts. This may require a comprehensive study.
Non starter cars through 1926 had series wired headlamps. Battery / starter cars had parallel 6volt bulbs.
A box of 10 went for $47 plus $7.50 shipping. Great buy if you have magneto lights...