MedPeel’s deep strength peels consist of the highest acid percentage in a given category. While these are the strongest in their category, it is important to note that each acid category penetrates the skin on different levels. For example, glycolic acid is not a deep penetrating acid, so even though the Glycolic 70% peel kit is classified as deep strength it only causes flaking, while TCA is the deepest penetrating acid that even the light strength TCA 10% will penetrate deeper and cause more peeling than any Glycolic peel.