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 GHK Cu Peptide: What It Does for Body Composition and Metabolic Health Subcutaneous Injection Sites and Instructions for Safe Self Administration The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline