Amazon.com: Neurogan GHK Cu (Copper Peptide) Neck & Face Serum 1,200mcg (1 oz bottle) : Beauty & Personal Care 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 Amazon.com: Neurogan GHK Cu Copper Peptide Hair & Scalp Serum 2400mg, 4% Copper Peptides Fast Absorbing, Water Based Formula for Hair Softness & Shine Cosmetic Dry Scalp Moisturizer Spray, Made in USA : Neurogan Health, GHK Cu Copper Peptide, Hair & Scalp Serum