Reloading ammunition requires attention to many critical cartridge dimensions" including case length" neck and base diameters" overall length" primer pocket depth" etc. Verifying these dimensions is quick and convenient with the Frankford Arsenal Calipers. The calipers are accurate to within .001-Inch. The calipers allow you to measure inside and outside diameters" plus depths. You will find them useful for many measuring tasks on and off the reloading bench. Packaged in a convenient and protective case.