An NSF program that additionally screens supplements for substances banned in competitive sport.
NSF Certified for Sport is a stricter version of NSF certification aimed at athletes. In addition to confirming label accuracy and good manufacturing practices, each batch is screened against a list of substances banned by major sports organizations.
It is the mark to look for if you are drug-tested for competition; for everyone else it functions as an extra layer of third-party quality assurance rather than an efficacy claim.