The new generation of Competitive Electonic's popular 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, they recommend their optional Indoor Lighting System (part# CEI-4100). Requires one 9 volt alkaline battery for operation (not included). Features: 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 wi Mfg: Competition Electronics