Another use of depleted uranium is in kinetic energy penetrators, anti-armor rounds such as the 120 mm sabot rounds fired from the British Challenger 1, Challenger 2, M1A1 and M1A2 Abrams. Kinetic energy penetrator rounds consist of a long, relatively thin penetrator surrounded by a discarding sabot. Staballoys are metal alloys of depleted uranium with a very small proportion of other metals, usually titanium or molybdenum. One formulation has a composition of 99.25% by mass of depleted uranium and 0.75% by mass of titanium. Staballoys are approximately 1.67 times as dense as lead and are designed for use in kinetic energy penetrator armor-piercing ammunition. The US Army uses DU in an alloy with around 3.5% titanium.