Question about Aarke Water bubbler II

I bought two "MySodapop" glass bottles in Germany that fit perfectly. (The brand was once mentioned here among the reviews.) You can watch them on YouTube, for example. They are extremely massive - 0.8kg - so quite heavy when filled. I can't imagine that they could burst when filled. Probably for safety reasons, they are sold in Germany with a jacket, a thin cover made of a kind of neoprene, which I immediately disposed of.

Thank you 😀