A holder for three (3) AA batteries! It's got an 8" long power cable with a 2.1mm DC jack at the end, and, oh yes, it's in classy Adafruit black.
This battery holder connects 3 AA batteries together for powering all kinds of projects. Three AA's add up to about 3.6-4.5V, a very similar range to Lithium Ion/polymer (Li-Ion) batteries. That makes them ideal for use with 3.3V projects. (Of course, you can't recharge them like Li-Ion/Polys, so don't try to plug this into one of our Li-Ion/Poly charger boards!)
Power cable is 200mm long with a DC jack with 2.1mm ID with center-positive polarity.