After a year of using GHK Cu both topically and going deeper than topicals (under my doctor's care), the difference in my skin is not something I have to squint at in good Expression and Purification of Recombinant GHK Tripeptides Are Able to Protect against Acute Cardiotoxicity from Exposure to Waterborne Copper in Zebrafish Amazon.com: Skin Perfection Copper Peptide Serum GHK CU 1% for Face & Hair Copper Peptides for Skin, Hair, & Scalp 1% Blue Liquid for Face, Neck, Body, Scalp Multi Use Serum Booster with Glow Peptide Protocol GHK Cu, BPC 157, TB 500 Neurogan Health