This is 12 Ga. Remington HyperSonic 3 1/2" 1 3/8oz #4 Shot NON-TOXIC Steel Shot Hi-Velocity Ammo. At 1700 feet per second, HyperSonic waterfowl ammunition is becoming more and more popular among waterfowl shooters because of it's top speed and unique Xelerator wad. Featuring a unique ignition chamber, the Xelerator wad allows for higher velocities while maintaining a safe pressure. In two different stages, the primer ignites a small powder charge then its primary powder charge to release the non-toxic steel pellets. Travelling at a high velocity, these pellets increase your chances of hitting your target the first time. This ammo comes packed in 25rd. boxes.