That is why they are ‘green’ unlike conventional batteries.
Citizen capacitors are charged by solar power whilst fitted in the watch.
ROYAL MAIL Destroying Parcels without warning or Compensation:
Royal Mail now consider Lithium Batteries including capacitors as dangerous goods and will no longer carry them, they will destroy any packages containing them without warning. Alternate carriers are automatically available to you at the checkout stage of your order unless you are outside of the UK. Unfortunately due to aviation restrictions, we are unable to send lithium batteries or capacitors outside of the UK.
Lithium batteries sent with a device there are restrictions, however lithium batteries not sent with a device is “Prohibited”.
Section from the Royal Mail Website:
Batteries that are classed as dangerous goods by the latest edition of the International Civil Aviation Organization’s (ICAO) Technical Instructions are prohibited. This includes wet spillable lead acid/lead alkaline batteries (such as car batteries), used alkaline metal, nickel metal hydride (NiMH), nickel cadmium (NiCd), zinc-air batteries, and damaged batteries of any type.
Lithium ion/polymer/metal/alloy batteries when not sent with, or contained in/connected to an electronic device, are prohibited.
Lithium ion/polymer/metal/alloy batteries are allowed when sent with or contained in/connected to an electronic device, but are subject to packaging, volume and quantity restrictions.