Dillon Oversized Powder Die Extra powder dies allow you to move your powder measure from tool head to toolhead without changing the "belling" adjustment. The XL powder die is necessary for the larger diameter cases, including 500 S&W, 50 AE, the WSM and WSSM family of cartridges, the RUM and RSAUM family of cartridges, .378 Weatherby and up, .338 Lapua, and 416 Rigby. This is for the die only, additional tools heads may be purchased specifically for your model as "An Addon Item"