What size is the OS-01 FACE bottle? Our standard size is 50mL. How long will my OS-01 FACE last? We estimate the 50 ml bottle of OS-01 FACE will last approximately 1-3 months when used as directed. How does OS-01 FACE compare to retinol? While retinol is often considered the golden anti-aging ingredient, it also has significant downsides, including increased irritation. Alternatively, our research shows that OS-01 FACE offers comparable benefits without the drawbacks. How should retinol be used with OS-01 FACE? Alternating gives the benefits of both products without interfering with absorption. If combining, you can decide which product to apply first, though OS-01 FACE achieves maximum penetration if applied first. What is the shelf life of OS-01 FACE? How should FACE be stored? OS-01 FACE has a shelf life of 24 months. All OneSkin products can be stored at room temperature away from direct sunlight.