The 3-Die Roll Crimp Set is an essential toolkit for loading straight-wall cartridges with precision. This set includes a steel Sizer Die that sizes the case and de-primes it—note that cases must be lubricated before use. The Expander Die is designed to expand the case to the correct diameter for bullet insertion, while also imparting a case mouth flare/bell to assist in bullet feeding. Lastly, the Seater Die expertly seats the bullet and ensures a reliable roll crimp. RCBS, founded in 1943, has a long-standing tradition of excellence in the field of handloading ammunition. As the leading manufacturer of reloading equipment for rifles and pistols, RCBS is committed to the precision and skill required for the reloading process. With a reputation built on producing state-of-the-art products, RCBS assures quality and performance in every item they craft. Trust RCBS's industry-leading expertise for your reloading needs.