I always keep extra O rings for my Inferno battery, however, not all O-rings are the same as when I bought my Inferno kit back in Feb-Mar 2013. Sometimes I have to try a few to get the right seal. Please have R & D double check these O-rings thickness. A tight seal is required for good use. I must also thank Volcano as an almost ex smoker for 51 yrs, down to 4-5 cigs a day.