The Hornady Cam-Lock Case Trimmer features a micro-adjustable cutter that allows for length changes in increments of 1/1000” without moving the case. The one finger case cam lock secures the case in place with just a touch, another touch is all that is needed to release the case. All trim lengths are measured from the head of the cartridge. Large diameter, replaceable cutting head trims cases up to .50 caliber in diameter with a tall frame to prevent banging knuckles on the bench. *Note: only use Hornady brand shell holders with this trimmer, other brands are not compatible.