Review on SumoLink 4-Pack ESP8266 ESP-01S Serial Wifi Wireless Module, Arduino-Compatible by Brent Mosley

I almost ordered these after reading the reviews and seeing the mention that this is 512k. Seller should re-use old sales pages with new/updated items as these ESP-01S are definitely 1MB just like all ESP-01S. I only used one and tested another. Both worked great. I'll update this review if I run into any issues with the remaining two. Before you download your sketch/firmware, do yourself a favor and erase the chip using Flash Download Tools. Also, feel free to grab a pack of these if you're on the fence! You definitely won't find a better price on a four-pack this side of the Pacific.