Specification: Weight: 6.70g Power supply: 2.2V to 3.6V Operating voltage: 3.3V Logic level: 3.3V Mounting holes diameter: 2 holes, 3mm diameter Integrated dual-mode Bluetooth 4MB Flash Memory Maximum serial baud rate: 256000bps Dimensions: 50mm x 25mm (1.97in x 0.98in) Feature: Latest ESP32 version: REV1 WiFi Bluetooth 4 MB Flash interface Default firmware: AT firmware Lithium battery connector, the maximum charging current of 500 mA Maximum baud rate: 256000 bps