We have formulated 4 levels of varying strength (starting at Level 1 0.25%, to Level 4 1.0%), allowing every skin type and experience level to enjoy the benefits of retinol at a pace that feels comfortable. Each skin will have a threshold of how strong a retinol it can tolerate! Some skins may find that Level 1 or Level 2 is their ideal long-term match, while others may gradually build up to stronger concentrations, such as Level 3 or Level 4. Introducing retinol slowly allows us to monitor how the skin responds and minimise the likelihood of irritation, dryness and sensitivity. Once the skin has adjusted and is tolerating its current strength well, you can decide whether progressing to the next level is the right step for you.