Advanced GHK Cu Face Cream 2400mg 4% Firmer Skin Neurogan Neurogan Health Defy GHK Cu (glycyl L histidyl L lysine) is a naturally occurring copper binding peptide found in human plasma. As levels decline with age, so may its support of the biological processes involved in collagen production, skin GHK Cu Peptide Serum 30 ml, Copper Peptide Serum with Hyaluronic Acid for Tightening, Collagen Boosting GHK Cu Peptides Serum TryDeloura