Have Weibel send you the installation manual, then it will be clear. Otherwise, you can also find a lot of information about it on Weibel’s website.
The Weibel box is basically just a flap that is mounted on the outside of the wall.
You have to lay a pipe through the wall yourself plus a very small tube for the power cable to the flap.
The Weibel flap covers a certain maximum pipe diameter. If the pipe is smaller, it doesn’t matter; the flap is simply mounted over the pipe end. The flap doesn’t care how thick the pipe is (unless it would be too large, but common sizes are covered).
The mentioned power cable is then routed inside and connected to an "intermediate plug." Your exhaust hood is plugged into this "intermediate plug." The intermediate plug normally goes into the socket in the wall.
The intermediate plug detects when the connected device (i.e. your plugged-in exhaust hood) is consuming power. When it detects this, it sends a signal to the flap to open. If the hood no longer consumes power (because you turn it off), it sends a signal that the flap should close again.
Extremely simple and independent of most construction types.
To make the flap really 100% windproof at the front, it is sealed all around with rubber gaskets and possibly some sort of joint sealant.
It doesn’t really seem insulating to me, but the alternatives would be either products with pressure flaps, which are never 100% windproof, or boxes with highly technological devices, which also don’t pay much more attention to an insulation layer.
I will check again directly with the manufacturer how thermal tightness is supposed to be achieved in the closed state.