Product description:
Model:ESP8266
ISM 2.4GHz
PA +25dBm
802.11b/g/n

Warnings:

1.This module requires a 3.3 volt supply for VCC, and 3.3V logic.
2.It is not 5V tolant,Connect RX or TX on 5V Arduino will destroy this module.
3.You must use a logic level converter, or a 3.3V Arduino
4.The 3.3V supply on the Arduino Uno has inadequate current capabilit to power this module.
5.You must provide a separate,higher 3.3V supply(about 300mA or better)

Package included:
2 pcs ESP8266 ESP-07 Remote Serial Port WIFI Transceiver Wireless Module AP+STA-