1×Adafruit METRO M0 Express, black PCB with gold plate on pads
4×Rubber bumper to keep the board from slipping off

ATSAMD21G18 @ 48 MHz with 3.3 Vdc logic/power

256 KB of Flash + 32 KB of RAM
2 MB SPI Flash chip
No EEPROM

32.768 kHz crystal for clock generation & RTC

3.3 Vdc regulator with 500 mA peak current output

1×Power on/off switch
1×Reset button
1×RGB NeoPixel on pin #40 for any purpose
1×Red LED on pin #13 for general purpose blinking
1×Green LED for indicating power
1×LED for indicating RX in active
1×LED for indicating TX in active

14×D0~D13 digital I/O, with D0~D1, D4~D5, D8~D9 capable of behaving as A6~A11 analog input
6×A0~A5 12-bit analog input, with A0 capable of being a 10-bit analog output (DAC)
1×Pair of SCL and SDA for I2C
1×Male header in 2×3 form factor for SPI with SCK, MOSI, and MISO
1×USB type Micro B port for 5 Vdc power
1×2.1 mm center positive barrel power socket with polarity protection for 7~9 Vdc power
1×SWD interface for trace-debugging
4×Mounting hole

USB native support, comes with USB bootloader and serial port debugging
Hardware Serial, hardware I2C, hardware SPI support

71 mm×53 mm

13 mm with barrel jack

20 g