Shooting Chrony 7000020 Alpha Chronograph, Red Measures the speed of bullets, arrows, etc. from 30 feet per second to 7000 feet per second. Chrony Cornograph Measure speed of bullets Alpha Chronograph Velocity stays on display until you shoot again. Delete individual shots from memory (with automatic adjustment of Statistics) Powered by a single 9 volt battery. Measures speed within .5-Percent accuracy.