9V Batterry Arduino

A 9 volt battery snap terminated in a 2.1 mm barrel jack, so a PP3 battery plugs straight into an Arduino's power socket with no wiring at all. The simplest way to make an Arduino project portable for a demonstration or a competition. Be realistic about run time: a 9V battery holds relatively little energy and an Arduino with modules attached will flatten one within hours. Plugs straight into an Arduino power jack; No wiring or soldering required; Makes a project instantly portable; Correct centre-positive polarity for Arduino