These Blank Cartomizers or Empty Cartomizers are used for E8 or U8 models. The Blank E-Cartridges can be used to refill the E-Liquid with whatever flavor you want.
When you refill the Empty E-Cartridge, please do not put too much E-Liquid at one time. Otherwise you may get leak or inhale some E-Liquid into your mouth.
For the detail information regarding how to refill the Empty E-Cartridge, please go to the link: How to Refill E-Liq