I have had two Double Barrels just stop working on me. No discernable reason and certainly not hard used (both were house mods). The mod just stops unaccountably. The first time I thought - okay sometimes you get a bad mod. But twice? I've heard others have the same issue too. And no - it is not juice leaking into the chip (which should be protected bit is not). Also had an issue with the Tac. Despite saying it accommodates 21700s it does not. It is also not so easy dealing with them. If like me you get a mod on a trade without a receipt they don't even look at it. So I'm done with Squid.