This can be a disposable unit(singl-use), you are not supposed to open them. Nonetheless, these equipment may be refilled but it is not recommended because the lifetime span of the coils is made to be that on the juice inside of the product. As the maker requirements the serial range https://grabba-leaf-gold-edition98516.blogdanica.com/27868772/the-5-second-trick-for-backwoods-singles-dark-stout-cigars-pack