As others have said, that is a heat gun.
HL designed their PCB, and initially they were hand picking/placing components, potentially outsourcing eventually. Later they purchased their own pick and place machine. This allows for rapid prototyping amongst other things.
This picture is showing someone fixing botched boards. Either a circuit had been bridged, or a component was broken.
This specialised and expensive heat gun is targetting 400+°C convection airflow to a particular component, melting the solder and allowing it to be plucked and removed by those tweezers.
Considering the size of the board, the technical limitations of adequately fixing boards with that methodology is a key reason the repeat faults have been so abundant. It's basically pretty difficult (conceptually easy, but it's tricky work), and as someone who was doing that kind of work during HLs pre-ordering fiasco, it's a big reason why I have been so patient with HL.
What they've done is seriously so much hard work, I really appreciate it.
I was intending to make my own vape before I found these guys project, and it exceeded my design ideals so what could I do but support their design efforts.
Same!
I have a couple of friends with great units, and I have been using one for an extended weekend away.
It's no sublimator, but it is such a good device. I can't wait to get mine back.
I enquired to HL about a few things over the week.
I asked about what processes they are bringing in-house, and if they could explain why they are confident about increased robustness.
They sent me the dot points from the latest update, but they further said this;
"Your patience is appreciated and we will be sure to keep you updated as we get closer to returning your device. Much of the processes and assembly techniques are proprietary and can't be shared, especially on a public forum. We assure you that the Hopper is going to be improved from these changes and that the company is not going out of business."
I went on to ask if they would extensively upgrade the entire device so all units sent out would be the same iteration. I mentioned the back-end single click switch as an observed difference.
"We plan to replace all internal electronics. I can put a note that you'd like a new Backend that requires only one click to turn it back on."
So, it seems enough is changing and it should be good for everyone. It's interesting to note about the back-end request, I'll see how that pans out.
Interestingly enough, those kind of devices would be the most expensive, most accurate convection vapes.
When I was using one, if it didn't belong personally to our engineer, I'd have loved to mod it to a glass bowl and bong!
Oh yeah,
@JoeMama the compressed air is to be sprayed directly into the heater from the chamber side, I don't think they recommend blasting into the air holes themselves.