RCBS Bottleneck Die sets include a full length sizing and decapping die, and a bullet seater and taper crimping die. The Full Length Sizer Die has an expander decapping unit to remove the spent primer while expanding the case mouth. Vent holes prevent case damage caused by trapped air or excessive lubricant. The Seater Die includes a bullet seater plug and built in roll or taper crimp as appropriate for the particular cartridge. Shell holders sold separately.