How GHK Cu Tightens Loose Skin: Evidence & Protocols PEPTIDE SPOTLIGHT: GHK Cu (Copper Peptide) Loose skin. Crepey texture. Dull, tired looking skin. Let's talk about the peptide that actually supports skin firmness from the inside out GHK Cu is Amazon.com: QUBIT GHK Cu Copper Peptide Face Cream 4% Peptides Moisturizer for Fine Lines, Wrinkles, Firming, Deep Hydration & Collagen 2400mg GHK Cu for All Skin Types, 30g : Beauty & Transform Your Skin with GHK Cu Benefits Amazon.com: QUBIT GHK Cu Copper Peptide Face Cream 4% Peptides Moisturizer for Fine Lines, Wrinkles, Firming, Deep Hydration & Collagen 2400mg GHK Cu for All Skin Types, 30g : Beauty & USA Copper Peptide GHK Cu Powder, DIY Blue Copper for Making the Best Face Cream