ESP32-PICO-KIT V4 is a mini development board produced by Espressif. At the core of this board is the ESP32-PICO-D4, a System-in-Package (SIP) module with complete Wi-Fi and Bluetooth functionalities. Comparing to other ESP32 chips, the ESP32-PICO-D4 integrates several peripheral components in one single package, that otherwise would need to be installed separately. This includes a 40 MHz crystal oscillator, 4 MB flash, filter capacitors and RF matching links in. This greatly reduces quantity and costs of additional components, subsequent assembly and testing cost, as well as overall product complexity.
Espressif ESP32-PICO-KIT WiFi/WLAN+Bluetooth Module – [Link]