Ordered a few 510XL DC cartos. 2 of them had a very tight draw on them and after looking, the two are missing an air hole at the bottom near the threads. They only have one where the others all have 2 holes. Hey now...how did those get past QC? Needless to say I am not using them because they get friggin hot! Have to pull too hard on them to get any sort of decent vapor going.
