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 GHK CU Copper Peptide Face Serum Robyn's Tack Room ROBYN'S TACK ROOM Vital+ Hair Copper GHK CU Serum Hair Therapy Serum Daytryp RX Intense Copper Binding GHK Cu 5% +Palmitoyl Oligopeptide 0.3% Repair S Chebo Clinic