Trim the case once-never trim again! The X-Sizer Die looks like a regular Full Length Sizer Die. Inside, the die features a specially designed mandrel with an expander ball and decapping pin attached. The mandrel is what the X-DieA(R) is all about. The patented X-Sizer Die eliminates the need for repeated trimming after an initial trim of .020" off the maximum case length to standardize the case. The X-Die doesn't shorten the length of the case: the mandrel reduces the growth rate as the case grows as a result of the case mouth-contacting the mandrel during sizing. Because of an extremely close tolerance between the mandrel and die neck wall, the neck wall of the case d Mfg: Rcbs