PCA Skin® 4% Pure Retinol Peel… What is it, and why do you want it? A blend of 4% pure retinol and anti-oxidants, PCA Skin®’s first pure retinoid peel improves skin texture, brightens and evens skin tone and diminishes fine lines and wrinkles through accelerated cellular turnover. [box] What is retinol? A first generation retinoid,