You can not go by the date on the box to tell what version. They are using the 06/16/10 boxes even for the ones manufactured after 07/21/10. I received some that has the June date and emailed them to ask. Was told that they are using the old boxes, but the cartos were made since 07/21/10. And if that is the truth or not from them, who knows.
cos, if you overfill, the excess will leak out the bottom. If filled right they do not leak at all. I left one sitting upside down for a couple hours and not one leak.
They run a tad too hot for me on a true 3.7v mod, but on stock 510 batteries, an Ego battery and my Lazer mods they are not bad. I have not experience any burning taste or signs of burning at all in a week with 2 of them. Even dry burned one of them. I do occasionally get a harsher dry hit if I've been using them too hard, but a quick turn upside down and a minute to rest and they are fine again.
The hit on them reminds me of a Joye 2.2 ohm 510 atty on a true 3.7volt mod. I imagine a lot of people will enjoy these just for that.
Happy Vaping!!