. This set of acoustic guitar keys, mainly adjust the melody of the guitar strings. A tuned acoustic guitar string won't come loose easily. With these tuning pegs, you can tune your guitar strings quickly and accurately. The high-quality internal gear effectively prevents the screw from slipping. These tuning pegs are compatible with acoustic guitar and good rust prevention. Specification:Material: Metal + Plastic Color: As the picture shown Diameter: Approx. 6mm/0.23 inchPackage Included:6pcs Acoustic Guitar Tuners (3L+3R)Note:Please refer to the measurement. A small measurement error is acceptable within the normal range. There may be a slight color difference due to monitor, camera or other factors, please refer to the physical item.