RCBS Neck Expander Dies are specifically designed to flare the inside dimension of only the case neck to ensure perfect alignment of the bullet during seating. FeaturesExpands the inside of the case neck of your brass casingsEnsures perfect alignment of the bullet during seatingFlares the inside dimension of the case neck while leaving the rest of the case body untouchedMade with high-quality materials and precision manufacturing techniquesProvides consistent results over time