The innovative Model 1900-24V is a pair of No. 6 units which, used together per included instructions, produce a 24 volt DC output to power many self winding clocks including Self Winding Clock Co. long distance billing timers (Telcos) and Stromberg hourly vibrating winders.
If you own one of the smaller ATO style clocks which uses the "Horolovar" style replacement system, consider this unit. It will provide a steady, non-varying 1.5 volts over the full battery life, resulting in a stunning improvement in timekeeping. Replaceable AA Batteries included and installed!