The Hornady Case Neck Thickness Gauge is the accessory to the Concentricity Tool that offers the next step in ultra-precision reloading. Its .0005 increment dial indicator helps identify neck thickness variations so you can sort and measure case necks or verify your neck turning operation - ultimately enhancing accuracy. Includes the following pilots:1- 22 cal | .224"3- 6mm | .243"4- 25 cal | .257"5- 6.5mm | .264"6- 270 cal | .277"7- 7mm | .284"9- 30 cal | .308"13- 338 cal | .338"15- 35 cal | .358"19- 45 cal | .452"