Personally I think these pen/cigar vapes, should be illegal as they are electrically unsafe and can harm. A good vape, as several protections, coil short circuit, undercharging, overcharging, battery short circuit as you have put them in the wrong way, auto cut off, so if you have been firing it for too long (say in your pocket).... also some have rate limiter to cut of puf time per minute.
Those pen they are unregulated and no have protection, They are dirt cheap like HK$40 vs HK$350 of what a normal vape costs. The big risk is when someone puts a battery that has no protection. But typically these things are blow up as they are dropped and the short circuit the battery or the button gets stuck or you leak juice into it and then is firing constantly... until they catch fire or the battery blows up.
Feeling Lucky?
I personally wouldn't touch a pen/cigar vape that doesn't have a screen and adjustable power, as it most likely means it has no protection.