This sweet little chronograph fits in the palm of your hand so you can take it anywhere. It's a great item for referees to instantly end arguments about whether somebody's gun is hot right on the field. Comes with instructions and a hardy plastic carrying case with foam interior for protection. It measures speeds from 150 to 450 f.p.s., and runs on a 3-volt lithium battery that provides around 30 hours of operating time. Size: 2 1/2" x 3 1/2" x 1 3/16".