GHK Cu (copper peptide) is a science backed anti aging compound that supports collagen production, skin regeneration, and overall skin health. Used in both topical serums and subcutaneous Amazon.com: Skin Perfection Copper Peptide Serum GHK CU 1% for Face & Hair Copper Peptides for Skin, Hair, & Scalp 1% Blue Liquid for Face, Neck, Body, Scalp Multi Use Serum Booster with GHK CU Peptide for Anti Aging & Skin Repair ElixerMD Turn Back Time with GHK CU Peptides Meet one of the most powerful anti aging peptides in skincare GHK CU. This advanced peptide helps to: Tighten and firm loose skin