ESP8266 ESP-01 based on ESP8266
Do not power it directly from your 5V development board it is 3.3v
Specifications:
802.11 b/g/n
Wi-Fi Direct (P2P), soft-AP
Integrated TCP/IP protocol stack
Integrated TR switch, balun, LNA, power amplifier and matching network
Integrated PLLs, regulators, DCXO and power management units
+19.5dBm output power in 802.11b mode
Power down leakage current of <10uA
1MB Flash Memory
Integrated low power 32-bit CPU could be used as an application processor
SDIO 1.1 / 2.0, SPI, UART
STBC, 1×1 MIMO, 2×1 MIMO
A-MPDU & A-MSDU aggregation & 0.4ms guard interval
Wake up and transmit packets in < 2ms
Standby power consumption of < 1.0mW (DTIM3)