This is a .45 caliber bullet in a .50 caliber sabot. For use in .50 caliber muzzleloaders. The new MZL Maximus high BC muzzleloader bullet was designed for use in in-line muzzleloaders and could possibly be the most accurate muzzleloader bullet ever made. These bullets are machined on a CNC Swiss style lather out of solid copper bar stock and will function down to 1300fps. This 12 pack comes with red Harvester crush rib sabots. Mfg: Cutting Edge Bullets