It is a Program Downloader or Burner for ESP-WROOM-32 ESP-32 WIFI Wireless Module. It has output all GPIO ports for user debugging. 

Specifications:

•  Applicable to the firmware burning test of four modules: ESP-WROOM-32, ESP-WROOM-32D, ESP-WROOM-32U, ESP32-SOLO-1
• Support one-click firmware download function
• Safe and reliable, small size, long service life
•  And has a power indicator light, burning indicator light, serial port communication indicator light
•  Lead-out all IO ports, which can be used as the smallest system development board or a fixture for small-batch programming

Package Includes:

1 x ESP32 WROOM Program Burner/Downloader