This is ESP 8266 ESP8266 serial WIFI wireless transmitter module gain antenna MT76813DBI Module.
With this external antenna, you will increase the WiFi range in your Raspberry Pi Zero W or any another devices.

Features :

Radome material: polyurethane
Flexible cable
Stable signal
Best for indoor applications.
Connector: IPX female to SMA-KY
Frequency(Hz): 900/1800
Gain: <3 dB
VSWR: <1.5