The X Die Mandrel Assembly unit features an expander rod and ball and a decapping pin. It's used with The X Die Sizer to de-prime the case and expand the neck. X-Die Mandrel Assembly unit is an essential component used with The X-Die Sizer Features expander rod and ball and a decapping pin to de-prime the case and expand the neck X-Die Sizer and Mandrel Assembly work together to provide unparalleled consistency and accuracy in your reloading process