This Winchester PDX1 Defender Combo Pack contains – 10 .4120 rounds 0 gauge rounds and 10 .45 colt cartridges. These rounds belong to Winchester’s PDX1 line of bonded ammunition which is the top of the line in personal protection ammunition. It simply can’t be beat. The PDX1 line of ammunition features Winchester’s proprietary bonding process that securely welds the jacket and lead together for controlled expansion. Additional features include a hollow point six-segment jacket notching and a nickel-plated shell case to ensure smooth chambering and ejection.