If you have a cleaning rod and a set of calipers, you can now determine the optimum OAL for any bullet in less than two minutes. This simple kit consists of two clamps that easily attach to any cleaning rod, ¼” in diameter or less. Simply insert a cleaning rod into the bolt face and install one clamp at the end of the bolt face. Then remove the cleaning rod and insert a round into the chamber. Next, touch the cleaning rod end to the back of the round and attach the second clamp at the end of the bolt face. Finally, remove and measure the distance between the two clamps or use as a gauge to check the seating depth set-up during your reloading sequence. It works on all rifles.