Ive had @sumanurica in my routine for almost a year now, so adding the new GHK Cu Repairing Serum felt like the perfect next step , Its lightweight, calming and layers beautifully, especially on Central mechanisms underlying the negative and positive feedback Download Scientific Diagram Sumanurica GHK CU Repairing Serum VS Numbuzin No. 6 Deep Sleep Mask GHK Cu Hair & Scalp Serum 2400mg 4% Less Shedding Neurogan Neurogan Health One of the questions we often receive about our products is: Why is the GHK Cu Repairing Serum stored in two part packaging? GHK Cu is an unstable ingredient that can slowly lose its effectiveness