The LE Wilson Adjustable Case Gage is designed for use on belted magnum cases. A floating insert allows set up for shoulder set back. You can set insert to your brass and measure your minimum and maximum case length. It should be noted that, although the belt on your cases provides proper head-space, the useful life of your cases will dramatically shorted unless resizing at the shoulder is held to a minimum. This case gage from LE Wilson adjusts to be used with rifles of the same caliber. This adjustment allows you to easily control the amount of resizing by measuring a fired case. Overall length can be checked with these gages. Cases are made of stainless steel. For use on belted magnum cases Floating insert allows set up of shoulder set back Set insert to your fired casings Measure min/max case length Made of stainless steel