The RCBS 3-Die Roll Crimp Set is engineered for reloading popular straight-wall pistol cartridges, delivering precision and reliability. This comprehensive set includes a steel Sizer Die, Expander Die and Roll Crimp Seat Die, each designed to perform a crucial step in the reloading process. The Sizer Die requires lubrication for smooth resizing of cases. The Expander Die ensures the case expands to the proper diameter, allowing for a secure bullet fit. The Roll Crimp Seat Die both seats the bullet and applies a 'roll' crimp to the case, preventing bullet movement during recoil and improving shot consistency. Ideal for reloaders seeking optimal performance and ease of use.