Serum nails MAVALA MAVA-FLEX. Serum for very dry, too hard and brittle nails that often absorbent strips are exposed to external factors such as chemicals, water, the sun, or internal, such as age, diet or hereditary tendency. It is made with a concentrated urea, calcium, lemon essential oil and vitamin B5, which penetrates the nail to hydrate and strengthen it. The result is healthy, flexible, shiny and soft nails that will stop breaking.