Superb craftsmanship: The guitar tuning keys are made of high-quality metal, with an elegant retro look and durable appearance, creating high-quality classic design buttons for tuning with ease, smoothness and precision. | Purpose: The tuner prevents the guitar from being exposed to the air, reduces rust and makes it more durable. High-quality internal gears can effectively prevent the screw from sliding. | Precise design: These sound bolts are compatible with 12-string guitars. It's perfect for replacing old and dirty tuning plugs, and it's also great for tuning guitars. Accurate engineering design ensures smooth adjustments every time. With these tuning bolts, you can quickly and accurately adjust your guitar strings. | Packaging content: 1 set with 12 string guitar heads, 12 rings and 14 screws. | Easy to install: equipped with screws and sleeves for easy installation. The adjusted guitar strings are not easy to loosen.