A dynamic microphone is so-called because it operates like an electrical dynamo, where the vibrations are received onto a diaphragm which has a coil attached to it, which is in close proximity with a powerful magnet. The vibrations move the coil through the magnetic field and this causes a current to flow within the coil, which is delivered as the audio output. In general dynamic mics are more rugged than condensers, making them more suitable for on-stage use. They can handle high sound pressure levels for example powerful vocals or snare drum hits and they usually have a built in shock mount to reduce handling noise. Their polar patterns are designed to pick up sound close to and in front of the mic whilst not picking up sound from further a field, for example sounds from other vocals or instruments nearby. This design also reduces the tendency to feedback (howl or high pitched whistle).