If you have purchased the Vapir NO2 Replacement Battery
then you will definitely want to have the External Charging Cord. The external charger allows you to charge the NO2's battery outside of the unit. This means you can use/charge one battery inside the NO2 while charging a second backup battery in the external charger. Never be caught with a dead NO2 with the External Charging Unit and Replacement NO2 Battery.
More from this brand: Vapir