The RCBS AR Small Base Die Set is a must-have for the serious reloader because it includes both of the dies you need to size and crimp your semiautomatic ammunition. Like all RCBS products this die set was crafted with superior attention to detail and made from premium products to ensure maximum durability and performance.The RCBS AR Small Base Die Set includes the Small Base Sizer Die which is specially designed for semiautomatic weapons. It also comes with the Taper Crimp Seater Die. Both of these dies ensure that your reloaded cases will chamber in AR-style weapons.