From my post in Travel Technology.

"A few years ago, I got something along the lines of these:
and never looked back. I haven't traveled with "multi-country" adapters since. One can debate about wattage, etc. But, these handle all my US-plug device needs. The company "Tessan" seems to have all different types of adaptors, capacities, etc."

-----

I've been traveling to/from living in SA on and off for the better part of 25 years and I've never even heard the terms "M" or "N" type plug. When I first went there for my first visit I brought an international converter brick thing that was a series of sliders, etc to get the "right" plug which NEVER stayed in the outlet to well. Gradually I moved to "double adaptors" from Spar and now, I find most if not all places have plugs that accommodate the aforementioned Tessan adaptors to get be a USB and USA plug option.