GHK Cu Copper Peptide Neck & Face Serum GHK Cu is a naturally occurring copper peptide known for its powerful role in skin repair, hair health, and cellular regeneration. Key Benefits: 1.Boosts Collagen & Elastin Helps improve skin firmness and elasticity. GHK Cu is one of my personal favorites for a lot of reasons, but I can say without a doubt that it's use effectively stopped and reversed, my receiving hairline. However, there are Copper Peptide Serum with 1% GHK Cu peptide, Argireline and Matrixyl 3000