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

Slight headache setting up. I had to flash it 5 times before it accepted my firmware. However, once set up, it worked as it should. When flashing with ESP, as soon as the name changes in ESP3D, you'll know it's being flashed. After that, if he has ESP and a bunch of numbers when connected to him via Wi-Fi, he still hasn't accepted. The default IP on mine with ESP3D before it was changed to local was 192.168.0.1 and the password before it was changed was 12345678. There are other IPs and passwords depending on the firmware.