heavy metals
third party tested means nothing until you ask three questions
Third party tested is on nearly every supplement website. It is also unregulated, and there are three questions that reveal whether it means anything.
the reason i will not buy a collagen product that will not show me its testing
Collagen comes from hide and bone, and bone is where the body stores lead. That is not a scare story, it is biology, and it is exactly why testing exists.