Changeable dia. neck bushing rifle dies. Sizing die w/self-centering changeable neck bushing that allows you to precisely set the amount of tension on the bullet. Neck bushings are not included. Seat dies feature micrometer adj. free floating and self centering bullet seating system with convenient bullet loading window...Can be used on progressive presses with exception of the PPc BR .221 Fireball & .22 Hornet.