Cellular Glow Copper Peptide GHK Cu Serum for Face GHK CU Peptide for Skin Rejuvenation Wittmer Rejuvenation Clinic The biological signal for full body skin tightening. If you want to visibly improve skin density, elasticity, and firmness, you need the right biological messenger. Enter GHK Cu (Copper Peptide). This powerful molecule GHK Cu Peptide Serum 30 ml, Copper Peptide Serum with Hyaluronic Acid for Tightening, Collagen Boosting