Topical GHK Cu: Skin Benefits, Best Forms, and Where to Buy GHK Cu is that feminine peptide every man should still be using if you want to age well. In this video I show the exact math and visuals for the dosage I take from a 50mg per ml vial using a standard 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