The definition of a sniper rifle is disputed among military, police and civilian observers alike, however most generally define a “sniper rifle” as a high powered, semi-automatic/bolt action, precision rifle with an accurate range further than that of a standard rifle. These are often purpose-built for their applications. For example, a police sniper rifle may differ in specs from a military rifle. Police snipers generally do not engage targets at extreme range, but rather, a target at medium range. They may also have multiple targets within the shorter range, and thus a semi-automatic model is preferred to a bolt action. They also may be more compact than mil-spec rifles as police marksmen may need more portability. On the other hand, a military rifle is more likely to use a higher-powered cartridge to defeat body armor or medium-light cover. They are more commonly (but not a lot more) bolt-action, as they are simpler to build and maintain. Also, due to fewer moving and overall parts, they are much more reliable under adverse conditions. They may also have a more powerful scope to acquire targets further away. Overall, sniper units never became prominent until World War I, when the Germans displayed their usefulness on the battlefield. Since then, they have become irrevocably embedded in warfare. Examples of sniper rifles include the Accuracy International AWM, Sako TRG-42 and the CheyTac M200. Examples of specialized sniper cartridges include the .338 Lapua Magnum, .300 Winchester Magnum, and .408 CheyTac rounds.