La Prairie Cosmetics. Skin Caviar Sleep Mask. High-tech cosmetic night treatment. It is a close-up mask and a night cream at the same time. It increases the firmness and elasticity of the face and purifies the skin from daily aggressions. Its formula consists of highly nourishing caviar extracts, which prolong the effects of the cream. Apply a film with the special brush to the cleansed face once or three times a week.