Sportsman Supply Inc. Shooting Chrony 7000044 Gamma Chronograph with Ballistic Chrony Printer, Silver Green Measures the speed of any projectile from 30 feet per second to 7000 feet per second. Comes with a huge 14 1/2 inch by 14 1/2 inch triangular shooting area. Comes with a 3 year warranty but will last a life time Powered by a single 9 volt battery. Measures speed within .5-Percent accuracy.