An omnidirectional siren is a siren that produces sound in a 360 degree radius at all times, instead of using a rotational mechanism which only outputs its full volume in one direction at a time. These sirens may use horns, skirts, or other means to project the sound outwards. Though omnidirectional sirens rarely outperform rotational sirens in raw decibel output or range, they tend to be much lower maintenance and do not rely on a rotator mechanism that would require belts, chains, or other parts that would wear out and fail over time. Omnidirectional sirens typically only have one moving part, which is the rotor. Omnidirectional sirens can be both vertical, or horizontally built, and may have one or more rotors and motors.