This site pairs this specific phrase with its Made-in-USA badge: produced domestically under close quality control.
Rather than a bare "Made in USA" statement, this site adds "under close quality control" — worth reading as a slightly more specific manufacturing claim, though still a brand-stated one rather than independently audited.
Worth reading "close quality control" alongside the separate GMP-Certified badge, since GMP is the more specific, named standard, while "close quality control" is this site's own general phrasing.