TSA knows about them. I take a complete kit of parts with me in my lugage as well as a couple full 901s on the plane plus... a battery box mod I built. I put the 901s in my laptop bag along with a 5ml bottle of juice. I also put the battery mod in my laptop bag with the batteries out of it, just lying in the pockets of my laptop case. No problems getting through any TSA so far. The kit of parts in my checked luggage was looked at a couple of times becuase the position of the zippers when I checked it in were different and the pocket where the kit was had been opened but everything is always there.
Please, please , please don't be stupid though and ruin vaping for all of us while traveling.
1. Don't vape on the plane. You don't have to. If you really must on a long flight, hold it in until there is no vaper.
2. In the airport, stealth vape there also. Do not let out a plume of vapor. In most people's eyes, where there's smoke, there's fire. Hold it in until there is nothing left to blow out. Sometimes you have to suck back a second time before exhailing.
I stealth vape in many airports and know one even cares but as soon as they see vapor, they're going to run and tell.
Make sure you stealth vape or you are going to ruin it for everyone.