The RCBS Carbide Sizer Die is part of the RCBS Carbide Roll Crimp 3-Die Set though it can also be sold separately. This sizer die was specially designed to help reduce the amount of time and hassle involved in the reloading process by eliminating the need for cleaning your cases before preparing them for reloading. The RCBS Carbide Sizer Die is able to do this thanks to the diamond-lapped tungsten-carbide interior ring included in each of the three dies which is so smooth that cases will never be scratched or stick.