The next generation of the ProChrono model based on a time proven design that has been measuring "almost anything that shoots" since 1985. Great for firearms shotguns archery airguns and paintball. Everything is included for outdoor use. For indoor use Competition Electronics recommends their optional Indoor Lighting System (part# CEI-4100). Requires one 9 volt alkaline battery for operation (not included).Features : Includes outdoor diffusers indoor diffusers not included On-board Bluetooth connectivity and more options with free apps for iOS Android Kindle PC and Mac Internal and external refinements with updates to the circuitry and enclosure design Built in full featured operating system with multiple shot string memory and statistics Sensing system compatible with a wide variety of light conditions and projectiles Faster internal shot clock for improved accuracy to +/- .5 percent or better Made in the USA quality at an affordable price 2 year warranty against defects in material and workmanship and a 1/2 price repair guarantee Over 30 years of experience in chronograph design and manufacturing Replaceable Alkaline 9 volt battery power (not included) for 20+ hours of operation Quality accessories and replacement parts at a reasonable price