Microchip RN4020-V/RM123 Bluetooth Chip 4.1, Maximum Output Power: 7.5dBm, Receiver Sensitivity: -92.5dBm, Supported Bus Interfaces: AIO, I2C, PIO, SPI, Supported I/O Interfaces: MCU, RN42, Serial, UART, Dimensions: 19.5 x 11.5 x 2.3mm, Length: 19.5mm, Maximum Operating Temperature: +85 °C, Minimum Operating Temperature: -30 °C, Width: 11.50mm