This overnight "sleep mask" formulation is an innovation because it blends the proven anti-ager retinol with hydrating hyaluronic acid to counteract any irritant effect.  It is designed to be layered over the Natura Bissé Diamond Extreme Oil for adjustable effect: because skin’s dryness or sensitivity can change from day to day, Dr. Sherber advises to smooth on more Oil under the Mask on days when more moisture is needed, and layer on more Mask on days when skin is ready for more active treatment. For added moisture, the Natura Bissé Diamond Extreme Cream is a perfect complement to the oil mask duo.