Copper Peptide (GHK CU) 1% Serum The Benefits & Risks of GHK Cu (WATCH BEFORE TAKING) A lot of people asked how I use GHK Cu (copper peptide) with a pen device, so here's a quick tutorial showing exactly how I do it. In this video I show how The GHK Cu pen works. But needles at home were never the answer. We took the same clinically backed copper peptide complex and put it into a serum you can use in 30 seconds,