ESP8266 ESP-01S Serial Wifi Wireless Module Compatible with Arduino
The ESP8266 microcontroller integrates a Tensilica L106 32-bit RISC processor, which is extra-low power consumption and reaches a maximum clock speed of 160 MHz.
80% of the processing power is available for the developers using.
And there's a lot of resources available for the ESP8266's development, and ESP-01S module is compatiable with Arduino.
Specification:
Package: DIP-8
Flash: 8Mbit
Dimension: 24.7*14.4*11.0mm
Serial/UART baud rate: 115200
Antenna: Onboard
Update Version of the ESP-01, totally compatible with ESP-01, while have a better performance and recommoned to replace the ESP-01 with ESP-01S