Worth a view. Yes your Vendor source matters. There's been a few individuals in the forum recently claiming they are "experts" and have so-called "extensive knowledge" who have criticized posts like this about China grey market testing reviews. When challenged, they can't back up their position with any verifiable evidence. Any vendor whether their product is made in China or US should be able to provide COAs that can be confirmed with a reputable 3rd party testing laboratory. Here’s a link to industry group American Peptide Association on how to read a COA. https://americanpeptide.co/blogs/blog/how-to-read-a-peptide-certificate-of-analysis Be aware of fake COAs that can't be cross-checked with 3rd party labs. Not manufacturer test, but independent test. Recent Clinical Paper (link is for pre-print) "Evaluation of Research Grade Peptides Marketed Directly to Consumers Reveals Extensive Variability in Purity and Measured Abundance." https://www.preprints.org/manuscript/202604.1748 "A total of 6441 peptide samples across fourteen compounds, including BPC-157, cagrilintide, CJC-1295, GHK-Cu, ipamorelin, PT-141, retatrutide, semaglutide, sermorelin, survodutide, TB-500, tesamorelin, thymosin beta-4, and tirzepatide, were analyzed." "The main finding of the study, that 41.6% to 71.1% of gray market peptides failed fundamental safety standards..." "..measurable endotoxin contamination was present in 15% of samples."