Tube for Zero Nega 2, choose your Zero Nega 2 size for the tube if you want to only change the tube on it. If you would like to change the SIZE of your whole Zero Nega 2, you have to pick up both tube AND frame + cap.
I have a Zero Nega 2 18650 size.
If I want to change the TUBE material/color: I pick up the 18650 tube
If I want to change the FRAME material/color: I pick up the 18650 frame + cap
If I want to change the SIZE: I pick up 18500 frame + cap AND 18500 tube
You can easily change tube and frame to switch from 18500 to 18650 battery and back, or you can change the color and material of your tube or frame.