Hornady Lock-N-Load Bullet Comparator Basic Set with 6 InsertsThe Hornady Lock N Load Bullet Comparator is perfect for the reloader looking to quickly and precisely measure seating depth of loaded ammunition from the bullet ogive to the base of the loaded round, to eliminate variation in seating depth. The comparator attaches to any caliper and measures cartridges from 17 to 45 caliber. When used in conjunction with the Hornady Lock N Load Overall Length Gage (Sold Separately) you will able to determine the