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 The GHK Cu Peptide: Benefits, Uses, and Why it's Known as the Regenerative Copper Complex GHK Cu Peptides Serum, Copper Peptides Serum for Face Tightening, Repairing, Collagen Boosting with Hyaluronic Acid Fragrance Free TikTok Shop Glow Peptide AH Clinics GHK Cu Copper Peptide Serum with Niacinamide, Hyaluronic Acid and Mushroom Extract 1% Copper Tripeptide 1 Anti Aging Formula, 1 oz