the tank is polycarbonate and works well but I vape pretty mild juice.
in regards to this post though I have an idea i was going to try (someday)
i was going to get some fatter orings and a pyrex tube from ibtanked to the correct length and just press fit it on, same with the top cap. this will remove the pocket friendly nature of the kayfun but i think it would work fine around the house.or even better grind off the threads and then you still have a lip for the tank to sit on.