Verifying reloading ammunition cartridge dimensions, including case length, neck and base diameters, overall length, primer pocket depth, etc. is quick and convenient with the Frankford Arsenal Calipers and Micrometers. The calipers are accurate to within .001" and the micrometers are accurate to within .0001". The calipers allow you to measure inside and outside diameters, plus depths. Packaged in a convenient, protective case.