Acetech i-Tracer Advanced BB Control System Computer Chronograph / Tracer / Burst Control Unit (Color: Black) Brand new , never used. I loading and batteries to test it. Works. Including batteries. Retail $109. Selling for $90. Features Standard Airsoft 14mm(-) negative threaded tracer made from high quality aluminum. High efficiency circuit with digital display with brightness controls. Devices communicate via wireless signal. Power saving / standby / and auto power off modes available Measure muzzle velocity (FPS/MPS), energy (Joule) and ROF (RPS/RPM) via iTracer Unit (14mm(-) negative thread) Programmable BB counter to count down or count up Low ammo warning + low battery warning + battery indicator for real time monitoring of battery level Programmable burst unit (2-10 burst / full auto) / SCU 8 channel memory Mounts onto standard 20mm / Picatinny / Weaver rails