The Hornady 366 Auto Progressive Shotshell Press is a great press for reloaders looking for a great progressive press for shotshell reloading. This add on accessory is a great option for reloaders looking for the ability to set the primer seater to one adjustment with no need to readjust the punch for different brands of hulls. This accessory can be retrofitted to nearly any 366 Auto Progressive Press set up for 12 or 20 gauge reloading. Notes: Allows the primer seater to be set to one adjustment eliminating readjustment when changing brands of hulls