Tuners Guitar Locked String Tuning Peg Key Machine Heads Semicircle Button for Acoustic Electric GuiDURABLE Locking tuners prevent the gear from being exposed to air and reduce the rust, which is more durable. EASY MOUNTING Guitar Tuners comes with screws, bushings and ferrules for easy mounting. NOT LOOSEN The tuned guitar string does not loosen easily. TUNE GUITAR ACCURATELY With these tuning pegs, you can tune guitar strings fast and accurately. PREVENT SCREW SLIPPAGE High quality internal gear, it's effective to prevent screw slippage. Locking