This is 12 Gauge Winchester Super-X 3" Magnum 1oz. Rifled Slug Ammo. For superior slug performance, you can't beat the stopping power of Winchester Super-X slugs. Winchester Super-X ammunition is made using the highest quality components to give consistent, dependable performance. Muzzle velocity of 1760fps. This ammo comes packed in 15rds. per box, 150rds. per case.