Arduino Leonardo without Headers is a microcontroller board based on
the ATmega32u4. It has 20 digital input/output pins (of which 7 can be used as
PWM outputs and 12 as analog inputs), a 16 MHz crystal oscillator, a micro USB
connection, a power jack, an ICSP header, and a reset button. It contains
everything needed to support the microcontroller, but this Leonardo board does not include headers.