After a case has been loaded a few times, it will stretch beyond maximum lenght and must be trimmed. The Cutter and Lock Stud works for all calibers, you'll need only one. The Case Lenght Gauge (pilot) and Shellholder must be ordered as Case Lenght Gauge and Shellholder for each caliber.Trims cases hand or eletrically. Can be used with an eletric drill to trim, chamfer and polish cases faster. Eliminates danger of long cases. Squares the mouth for more accurate bullet seating and exit.