Murad RESURGENCE Retinal Youth Renewal Serum Fast-acting serum with 3 retinol technologies visible improves key signs of aging in just 2 weeks. Gentle enough for nightly use. Clinically proven:users reported visible improvements in the 5 key signs of aging. Fewer lines and wrinkles, skin looks firmer, feels smoother, and is even-toned with a boosted glow (after 4 weeks)