This is a contact microphone for 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 a straight plug. It can be used in various situations such as brass bands and orchestras. It's in beautiful condition with no signs of use. It has the same functionality as the Korg CM-100.