The U.S. Bureau of Mines has developed a new method of making armor plate for military vehicles. The process was developed from the expendable pattern casting process (EPC) because it is ideally suited to making slot configurations required by the design of the new armor. While the advantages and economics of the EPC process were documented for casting aluminum, it had not been used to make steel castings. The new armor plate, designated P-900, is ballistically as effective as solid armor at equivalent thicknesses, but weighs 45% less. The armor has numerous oval-shaped slots in a regular array. The slots are at an angle to the frontal plane of the plate. This design is referred to as "add-on" or "stand-off" because it allows the armor to be spaced several inches away from the vehicle. When hit, P-900 causes a projectile to shatter into smaller pieces, each of which has only a portion of the total energy of the whole projectile. The small pieces have insufficient mass and velocity to penetrate the vehicle hull. P-900 armor offers many advantages: It is more efficient to transport, offers greater support economy, improves maneuverability, is easier to repair, and reduces vehicle fuel consumption. P-900 also is readily replaceable in the field, and its lightweight properties allow it to be retrofitted on most military vehicles without requiring a larger powertrain.