ProChrono DLX ballistic chronograph with improved accuracy specs and built-in Bluetooth is an improved model based on a time proven design that has been measuring “almost anything that shoots” since 1985! Great for firearms, shotguns, archery, airguns, a paintball. Everything is included for outdoor use. For indoor ensure hi brightness or use additional lighting. FEATURES:On-board Bluetooth connectivity, and more options with FREE apps for iOS, Android, Kindle, PC, and MacInternal and external refinements with updates to the circuitry and enclosure designBuilt in full featured operating system with multiple shot string memory and statisticsSensing system compatible with a wide variety of light conditions and projectilesFaster internal shot clock for improved accuracy to +/- .5% or better2 year warrantee against defects in material and workmanship, and a 1/2 price repair guaranteeOver 30 years of experience in chronograph design and manufacturingReplaceable Alkaline 9 volt battery power (not included) for 20+ hours of operationSPECIFICATIONS:Velocity Range: 20 – 9,999 feet per secondTemperature Range: 20-100 degrees FahrenheitSize: 16x4x3-1/4 inchesWeight: 2.1 lbsBattery Required: One 9-volt alkaline batteryBattery Life: Approx. 20 hours of operationCurrent Consumption: Approx. 20mAMounting Hole Thread: 1/4x20Guide Wire Size: 3/16×16 inchesMemory Capacity: Up to 9 strings of up to 99 shots eachMinimum Time Between Shots: 500 mSecShot Timing Resolution: 31 nSec (8000 counts @ 4,000fps) Crystal ControlledAccuracy: +/-.5% of measured velocity or betterBluetooth: BT2 and BT4LEAPP DOWNLOADS:Mobile App – iOSMobile App – AndroidDesktop App (PC & Mac)Download manual under ATTACHMENTS tab.