Another great thing about the in-line battery on a usb pass-
through... Very few USB battery packs put out the power needed to fuel the pass-through. The Kensington is one... 1.5A, but at around $50. Most are underpowered.
But... I picked up a Lenmar for $15. It only has 700mA output, which doesn't provide enough power to fire up an atomizer. But it IS enough to recharge the in-line battery. Soooo... I '
vape' on the in-line while it is recharging from the $15 power pack. Saved lots of money, and works like a champ.
Same thing with USB adapters for your car. They don't put out enough to fire up the atomizer, but work great with the in-line battery pass-through.