IGF-1 LR3 is an 83-amino-acid analog of insulin-like growth factor-1 in which the first three residues are replaced by arginine and the C-terminus is extended, markedly reducing affinity for IGF-binding proteins and prolonging receptor activation. This modified profile makes it a standard tool in muscle-growth, differentiation and metabolic signaling research. It is supplied as a white lyophilized powder at verified purity in sealed vials with batch traceability. Each batch is released only after peptide-content verification and purity assessment, and the corresponding records are retained for future reference. For projects requiring independent confirmation, we can arrange third-party analytical testing and share the results before shipment on request.