The RCBS Neck Sizer Die only is just one more example of the outstanding reloading parts manufactured by RCBS. The company is so confident in the materials used and manufacturing process that it provides customers with a lifetime guarantee.With this sizer die, only the neck of the case, opposed to the body and shoulder, are sized. This die ensures there is just enough space to keep the bullet firmly in place. As a result, the case life is extended and accuracy is greatly enhanced. Crafted from steel, this die is made to last.