GHK Cu Hair Growth Serum Proven Copper Peptide, $299 Topical or SubQ GHK Cu? Same molecule. Very different purposes. Topical you apply it on your skin. Think of it as feeding your skin from the outside. In a 12 week study of GHK Cu Neurogan Health, GHK Cu Copper Peptide, Hair & Scalp Serum Shed Copper Peptide Hair Growth Serum Take an Rx approach to hair health GHK Cu Copper Peptide Hair Tonic for Fuller Looking Hair 12 Week Supply (30 mL)