The Dillon Precision Accurized Micrometer Bullet Seating Die is built for a bullet diameter, and expands with a conversion rather than a second die. For a handloader who shoots more than one cartridge in a family - and most of us do - that changes the shape of the whole purchase. The Accurized Micrometer Bullet Seating Die is the only one taking into consideration the bullet profile by including two seating stems, one for tangent and one for secant projectiles. Quality-of-life features, like the re-zeroable detent micrometer, free float scale, and 1" of total travel are other aspects that make the die unique. FeaturesOne die, six interchangeable bullet diameters.Two seating stem profiles (tangent and secant) included in the box. Reduces marring on the bullet jacket. Super tight tolerances and low seating point virtually eliminate runout.