MAC Light Medium Sheer Mystery Powder ($65.00 for 0.56 oz.) is a sheer, pressed powder. Each year, MAC launches it with their “couture” collection (typically at the end of the year), and this is one of three shades. Light Medium is likely a good bet for NC/NW20. It has a mostly neutral undertone, and when sheered out, matches my forearm pretty well (which is around NC20). It also is available in Medium Plus and Dark Secret.