The Xcortech X3200 MK3 Chronograph is a BB chrono for use with airsoft guns. Measure your FPS (feet per second), Joules, and everything else on one handy screen. Uses a micro usb power adapter cable or 2x AA batteries to operate (cable and/or batteries not included) with this awesome device. Great for fields with its battery operation. Very accurate and speedy readings from this new chrono!