Not all copper peptide serums are formulated the same Before you buy one, make sure you're actually getting pure GHK Cu at the right concentration not just a diluted blend. We spent Amazon.com: Neurogan GHK Cu (Copper Peptide) Neck & Face Serum 1,200mcg (1 oz bottle) : Beauty & Personal Care Amazon.com: Bargad 5% GHK Cu Copper Peptide Face Serum Anti Aging Firming Serum for Fine Lines & Skin Renewal With 2% Niacinamide, Hyaluronic Acid, Alpha Arbutin & Centella Asiatica All Skin BioCellMED: GHK cu Copper Peptide Face Serum with Plant Stem Cell Cellular Glow Copper Peptide GHK Cu Serum for Face 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 :