The Audio-Technica AT831a Unidirectional Battery Lavalier Miniature Microphone is a high-quality microphone designed for professional audio recording applications. With a unidirectional polar pattern, this microphone is ideal for capturing clear and focused sound from a single source. The compact size and lavalier design make it versatile for use in various settings, while the brand reputation of Audio-Technica ensures reliable performance and high-quality audio reproduction. Some minor wear from normal use. Untested. Empty spot in case is for battery