The Necessary™ | Care For Your Body | Care For Your Planet The Rosemary Leave-In Mask an advanced leave-in treatment mask for use 1-2 times per week or as needed. Rosemary Leave-In Mask also includes Rosemary Extract and conditioning agents that smooth, soften, and enhance silkiness and a concentration of 5% Vegan Keratin—with the same amino acid profile as natural keratin—helps strengthen, restructure, and fortify weakened strands. Rosemary Leave-In Mask works immediately for smoother, shinier hair and over time to repair the look of damage, reduce breakage, and protect against external stressors. A multi-benefit finishing step in the Rosemary regimen—or a standalone treatment for healthier-looking hair with a rich, nourishing texture and is infused with the brand’s signature rosemary scent. Dermatologist-Tested. Hypoallergenic. Non-Comedogenic. Vegan. Color-Safe.