Skin aging is affected by your genetics, lifestyle, and environmental exposure. You can control the last 2 factors. I formulated my pH Optimal Retinol Series with this exact idea in mind. Four different levels of Retinol allow the concentrations to be delivered to you as you need them without Tachyphylaxis. And I chose air tight containers to protect the effectiveness of the active ingredients just as if I made it right in my office for you to take home fresh that day.