The Laneige Water Sleeping Mask is a leave-on overnight mask that is designed to provide intense hydration to the skin. The mask contains Laneige’s proprietary “Sleep-tox” technology, which is intended to help purify and hydrate the skin while you sleep. Other key ingredients in the mask include hydro-ionized mineral water, evening primrose root extract, and lychee extract. The mask is designed to be used as the final step in your nighttime skincare routine and is applied in a thin, even layer to the face.