MAC Studio Fix 24hr Smooth Wear Concealer 7 ml. #NC50. MAC Studio Fix 24hr Smooth Wear Concealer is an indispensable, delicious liquid concealer that, with its medium/full coverage, gives you an even and uniform coverage of everything from impurities to dark circles under the eyes. It is available in a multitude of shades, so there is plenty of opportunity to find the color that suits your skin tone. The small foam applicator feels comfortable on the skin and makes it super easy to cover areas that can be difficult to reach. The oil-free formula also ensures that the result never looks dry or lumpy.