These O-rings / Rubber Seals are used with the Kanger Subtank Nano Clearomizer found here. You can choose from a selection of colours or buy a 5 pack at a cheaper price per ring as at 5 Pack Subtank Nano O-Rings / Seal Rings.
Due to constant screw / unscrew of your electronic cigarette tank / clearomizer when refilling, rubbers tend to wear over time and when replacing the tank / clearomizer glass it is also advised to replace the rubbers to ensure no leakages occur which can loose costly eliquid inside the tank.
Please Note!! Subtank Nano NOT Included with the O-rings / Pictures are for illustration purposes only.