The three die carbide sizer die set includes powder through expanding die for charging the case with funnel or lee auto disk powder measure and seater die with built in crimp. Three die handgun steel die sets consist of a steel sizing die (requires case lubrication), a powder through expander die and a seater crimper die. Generally, this option is chosen for calibers that have a design other than straight walled because carbide is not practical for such designs.