GHK cu is a copper peptide. It's great for skin, especially when you combine it with other things. My favorite is DMSO and derma rolling. My first experience with copper peptides was Procytes GHK Cu Copper Binding Tripeptide Complex True Research Labs GHK Cu 100MG SSP Research New insights on the skin stack I posted earlier this year. RECAPPING: GHK Cu was developed by a company called Procyte in the 90's. I was an interested follower of Dr. Pickart's work GHK Cu 99%+ Pure Peptide Amino Club Amino Club