Lyman 7 mm Rem Mag Carbide Neck Size Die Only 7135214 The Lyman Deluxe Neck Size Die with Carbide Expander Button allows neck resizing without the use of inside neck lube. The die body is made from precision machined hardened steel and resizes only the neck of the cartridge. This leaves the rest of the case the exact size of the chamber it was fired in and extends the life of the brass compared to full length sizing. The expander assembly includes a free floating carbide sizing button that self-centers in the case neck. The carbide button is super hard and slick allowing it to easily pass through the case neck causing less case stretch than traditional sizing buttons resulting in longer case life and reduced case trimming.