This is a contact microphone for KORG tuners. It's a contact microphone that uses a piezo element to send vibrations directly to the tuner. The clip attaches to the headstock of a guitar, the bridge of a violin, the bell of a wind instrument, etc. It has an L-shaped plug. It can be used in various situations such as brass bands and orchestras. It's in beautiful condition with no signs of use. Korg