The MagnetoSpeed Sporter Chronograph Kit includes a display unit, bayonet-style sensor, v-block spacers, heavy duty strap, and ultra-compact storage container. The Sporter features a one-button cycling display, three sensitivity settings, quick-attach strapping system, and integral 3.5ft sensor cord. The Sporter was designed to fit barrels 1/2" to 1" in diameter, muzzle brakes and flash hiders up to 2.7 inches, and is best suited for rifle barrels and long-barreled revolvers. MagnetoSpeed Sporter Chronograph Kit