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 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 Regenerative & Cosmetic Research STOP MIXING GHKcu!!!! Peptides are very fragile and combining them causes them to further degrade, reduce stability, and destabilizes purity. Differences in pH interact with each other and significantly decreas stability.