Magnetospeed sporter barrel mount chronograph for rifles Features:-Simple, one-button cycling display (shows recent shot velocity & statistics, plug in to turn on)-Battery: 9-Volt (included)-Easy access battery compartment, no need for screwdriver to swap batteries-Three sensitivity settings for fine-tuning-Integral, quick-attach strapping system; with metal buckle & triad thumb nut-Proven technology with updated sensor design-Integral 3.5 foot sensor cordKit Includes:-Display unit-Bayonet-style sensor (Bayo)-Thick & think rubber V-block spacers-Heavy duty strap with thumb nut tightener-Ultra-compact storage container Other Features: Mounts on barrels.5"-1" dia.And muzzle devices up to 2.5" in length,compact led display, thick & thin v-block spacers, uses 1ea.9v battery, advanced data logging, mounts on barrel, three sensativity settings for fine tuning, for use with rifles only