Shop › Birch moisturizing sheet mask Image 1 of 1 Birch moisturizing sheet mask $4.00 ROUND LAB Birch moisturizing sheet mask is a hydrating Korean skincare treatment designed to deeply replenish moist and soothe the skin. Add To Cart Added! ROUND LAB Birch moisturizing sheet mask is a hydrating Korean skincare treatment designed to deeply replenish moist and soothe the skin.