2% GHK CU Copper Peptide Serum for Hair Growth and Scalp Care Copper Peptide Hair Growth Serum for Hair Loss & Thinning Hair Feline Skinscience Small molecules. Powerful results. Experience Peptide Power with Hairgenetix's advanced Copper Peptide Hair Growth Serum, formulated with 10% GHK Cu and 5% AHK Cu to support hair health at the follicle level. Helps Hair Growth Serum Intense with Copper Peptide GHK Cu