RCBS pioneered and developed 3-Die Sets for straight-wall rifles and pistol cases. These sets for straight wall pistol cases build off of that legacy. Each set features a steel Sizing die. The Expander die expands the case to the proper diameter to accept the bullet and also imparts case mouth flare/bell for easy bullet feeding. The bullet seating die then seats the bullet and puts on the appropriate crimp for the round being loaded. Features a hardened steel Sizer Die (case lubrication required) Expander Die to properly expand case to accept bullets Taper Crimp Seat Die for Proper cartridge headspacing Comes in a Green Box All RCBS dies are machined to exacting tolerances hardened and finished to the highest standards in the industry