The 5ml tube is not glass, some sort of acrylic fused with the cage. I'll be ordering one of these today after reading a review from someone whose opinion I respect.
You are correct, it is acrylic and cannot be removed from the metal housing. Guess using acrylic could be a concern for some who enjoy citrus or cinnamon flavoured juices. The 8ml is glass but does not utilize the metal housing.
I do not use a lot of rta’s so difficult for me to make comparisons. Machining is excellent, threads are super smooth. It is very easy to build on, tons of room for larger coils if that is your thing. So far no problems with wicking or leaking, no dry burns. Flavour is very good and air flow is fairly smooth - but given the airflow is directly under the coil, the type of coil may influence this.
If I had to find any negatives with the rta, it would be its smooth clean surface could be problematic when trying to disassemble and or adjust air flow. But outside of that, I’ve really been enjoying it.

