This ammo is for cartridge size .45 Winchester Magnum. The bullet is made from Brass. The diameter (caliber) of this bullet is 0.452. This bullet weighs 230 grains. This bullet leaves the barrel at 1600 feet per second. The ammo case is made from Brass. This ammo is a proven round for hunting. The bullet in this product does contain lead. This round is designed to be supersonic and travels faster than the speed of sound. The muzzle energy of this ammo is 1308 ft lbs. This product has been designed to be an effective choice for the ultimate in self-defense applications. The bullet in this product has a Sectional Density, (SD) of 0.16082476533569. SD is the ratio of an object's mass to its cross sectional area with respect to a given axis. It conveys how well an object's mass is distributed (by its shape) to overcome resistance along that axis. This ammo IS SAFE to use in a suppressor. The bullet in this ammo has a ballistic coefficient (G1) of 0.188 - Generally, the higher the coefficient, the more stable the projectile will be in flight. Each box of ammo contains 20 loaded pieces of ammunition. This ammo is manufactured by Underwood Ammo