Caldwell 4001147 Ballistic Precision Chronograph Bluetooth CompatibleCaldwell's Ballistic Precision Chronograph provides accurate velocity measurements across a wide range of shooting conditions. Higher accuracy was achieved by using a high speed 48 MHz processor and by designing a circuit with an advanced data interface that allows each unit to be computer calibrated at the factory after assembly. The end result is the ability to provide much better accuracy than other chronographs on the market (+ . 25%). Although