Material: This guitar tuner pegs with a zinc alloy construction. Tuning nails are anti-rust, anti-corrosion. It has stable working performance, durable and strong.  These are an excellent value featuring 15:1 ratios to get those pitch tensions up quickly. They incorporate an integrated set pin that follows the string lock knob so the pin retracts easily as the knob is turned making them less likely to get stuc.  Accurately: The gears are made of high quality, which can effectively prevent the screw from slipping. The tuned guitar cable is not easy to loosen and out of tune, and it can also react to the slightest turn.  Easy to Install: You need to drill tiny holes in the back of the headstock, the knobs are screw-mounted and can be replaced, each installation of the knob "axle" has an independent through-hole nut, If the lock doesn't go far enough on some tuners to lock the high strings. Solution is to put those on the low strings since they don't need to close the space.  Package Includes: 6 tuning peg machine head(3 pieces right&3 pieces left),6 nuts,6 washer,6 mounting screws. They locking assemblies add some additional mass which helps with sustain starved bolt on style beauties featuring knife edge floating tremolos.    Colour:black  Material:Zinc alloy    Package Contents:  6 x tuning peg machine heads(3 pcs right&3 pcs left),   6 x nuts,   6 x washers,   6 x mounting screws.    Only the above package content, other products are not included.  Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.