Adafruit 12mm Coin Cell Breakout Board
Simple but effective - this breakout board has a CR1220 coin cell battery holder soldered on and 0.1" pitch breakout pins for easy connecting. Great for powering very low-current projects, or adding a battery backup circuit to a real-time-clock or similar.
Comes with one fully assembled and tested coin cell battery holder and a small stick of 0.1" header so you can solder it on and plug into a breadboard.
Coin cell battery not included.