I like my cleito tank but the coils do seem to be hit and miss. I believe they had a bad batch that were wound too tight. Unfortunately, I don't know of any way to check which batches were affected. My original .4 coil went like 3 months before I needed to change it out. I bought some new coils and they aren't as good as the first - I have spitback and they last at most a week. Same juice, same power, same device. I'm soaking the used coils in some alcohol for a few days to see if I can reuse them.