This is a Espressif ESP32-WROOM-32U 4Mbit, 8Mbit or 16Mbit Flash WiFi Bluetooth Module.
ESP32-WROOM-32D and ESP32-WROOM-32U are powerful, generic Wi-Fi+BT+BLE MCU modules that target a wide variety of applications, ranging from low-power sensor networks to the most demanding tasks, such as voice encoding, music streaming, and MP3 decoding.
ESP32-WROOM-32U is different from ESP32-WROOM-32D in that ESP32-WROOM-32U integrates a U.FL connector. For detailed information on the UFL connector please see Chapter 10 in the datasheet attached.
Note that the information in this data sheet is applicable to both modules. Any differences between them will be clearly specified in the course of the document in the attachment.
Features of ESP32-WROOM-32U:
ESP32-WROOM-32 contains two low-power Xtensa 32-bit LX6 microprocessors
448 KBytes ROM for booting and core functions
520 KBytes on-chip SRAM
8 KBytes SRAM in RTC SLOW
8 KBytes SRAM in RTC FAST
1 Kbit of EFUSE, 256 bits MAC
IPv4, IPv6, SSL, TCP/UDP/HTTP/FTP/MQTT
Interfaces: SD-card, UART, SPI, SDIO, I2C, LED PWM, Motor  PWM, I2S, IR, GPIO, capacitive touch sensor, ADC, DAC, Hall sensor, temperature sensor
Flash Memory: 4Mbit or 16Mbit (Optional)