Lyman Stainless Pro Carbide Sizer Die die bodies are made of stainless steel which is noted for its toughness and anti-corrosion qualities. No more rusted dies! Pro sizing dies are equipped with highly polished carbide rings for the ultimate in wear resistance and reduced sizing force. The carbide rings have a generous radius on the mouth to allow cases to easily align on progressive presses. Rifle dies also include super slick carbide expander buttons to reduce case stretch. In addition, the sizing dies are equipped with a spring-loaded decapping rod system to ensure that the primer is forcefully ejected from the primer pocket every time.